Ian
Notorious member
INCOMPLETE DRAFT....will edit later
Back, by popular request. Here goes...
A few years ago I set out to understand and solve a few problems common in one way or another to virtually every cast bullet lubricant that has so far been devised. The principle and common issue with typical lube formulations of the time was that each may work very well for specific purposes or a certain range of conditions, but none I tried provided acceptable results across the whole spectrum of realistic shooting or storage conditions. Sensitivity to extremes of ambient temperature, changes in temperature, high rates of fire, hot storage conditions, various bore finish qualities, and to various amounts applied to the bullet were the principle issues I sought to improve with the ultimate goal being to work out a recipe which would serve virtually anyone's needs. A few others joined the project and contributed immensely to the generation of hypothesis and devising tests to isolate and evaluate variables. The approach I took to solving the problems was to begin tabula rasa and through basic testing, acquire a better understanding of the mechanisms by which a cast bullet lubricant actually works. Once the functional mechanisms were established, we began to identify, define, and isolate the failure modes. Determining the cause and correction of these failure modes tended to happen simultaneously through experimentation as different ingredients and proportions were tested and results observed.
The basic function of a good cast bullet lubricant boils down to a few simple tasks. First and foremost it serves as a friction-reducing and wear-preventing barrier between bullet and barrel, though it was soon discovered in testing that the barrier can and does function in several distinct modes that can be described as deep-drawing lubricant, dynamic film lubricant, and boundary lubricant. The barrier itself between bullet and bore must provide consistent friction qualities throughout the extremes of operating ranges and lubricating modes if group consistency is to be maintained. Our friend Eutectic coined the acronym CORE, or Consistency Of Residuals Encountered, to describe this attribute that a lube and its residue must have both before, during, and after the shot is fired so that each bullet lands in the normal group, be it the first shot on a cold morning or the last from a hot, fast string of fire. I find the acronym CORE invaluable and will refer to it often. Bullet lube serves a very dynamic role within the gun and must transition from a near-solid with very high viscosity and film strength, to a pressurized liquid, to (in extreme cases of poor bore condition or very high sliding speed/pressure) a boundary lubricant where the solids within the compound act as a dry lube which will perform in the absence of the liquid film. In order to satisfy both CORE and wide temperature needs, the barrier which lube provides must have the same net friction characteristics under ALL of these conditions, at any point in the barrel, with any given load or gun combination in any weather. Another important task that a bullet lube performs is what Glen Fryxell has referred to as "ballistic stop-leak", put another way, a "dynamic obturation aid" which helps maintain an absolute seal between bullet and bore as the bullet encounters the virtually inevitable, minute surface and dimensional imperfections of the lands and grooves. At high velocity, the driving-side of the lands puts extreme pressure against the companion surface of the engraved bullet, resulting in accelerated friction, heat, and wear of the bullet metal, all which contribute to the bullet surface failing and ultimately, loss of obturation at the trailing side of the engraves. The barrier quality of the lube is critical to prevent this metal failure, but even if it succeeds in preventing drive-side wear, minute barrel imperfections can still cause the dynamic film to be lost on the other areas of the bullet/barrel interface if the lube viscosity becomes too low for the pressure and degree of barrel imperfection. Developing lube chemistry that will allow a certain necessary viscosity reduction during the shot for dynamic film lubrication, yet control viscosity breakdown to prevent loss of obturation in rough barrels proved essential to achieving a sturdy, multipurpose lube and is still one of the biggest challenges for any recipe. The final principle concept of lube function has been described by Fiver, and is the only part involving exterior ballistics: Lube remaining in the grooves as the bullet exits the muzzle should "either all stay or go" so that it doesn't depart erratically along the path to the target and cause the bullet to veer. Much experimentation revealed that the "all go" is much easier to achieve with a universal lube than "all stay", so my efforts focused on achieving immediate jettison reliably under just about any condition by manipulating the physical characteristics of "tack" or adhesion, plasticity, and thixotropy. So, in a nutshell, the principle functions of bullet lube boil down to keeping the bullet's surface from contacting the barrel steel, maintaining a positive seal (obturation) between the bullet and barrel, and then when it's job is done at the muzzle, getting off the bullet and out of the way as soon as possible so as not to become a bullet balance liability later.
Having conceptualized the function of bullet lubricant, the next task was to determine how the problems we observed on targets or in the guns related to failures of function, and which function to address with a solution. The problem of cyclic flyers can be loosely attributed to "lube purge", or a gradual accumulation of deposits in the bore which the succeeding bullets "run over" without apparent difficulty until the whole mess goes out at once with one shot, causing a flyer, and the process repeats. I don't claim to understand the mechanisms of this phenomena thoroughly, and like many things shooting-related can only be observed through secondary indicators, but at this point I have concluded that lube recipes which leave more lube or components of lube behind than is purged each shot because the oil in the formula has too high of a viscosity index and doesn't thin enough to evacuate predictably are the main cause of this. Cold-barrel flyers are another burr under the cast-bullet shooter's saddle, particularly with regard to hunting applications where the first shot point of impact needs to be absolutely consistent and predictable. Correcting the cold-barrel point of impact shift is almost entirely a function of effectively managing CORE by creating a lube that effectively maintains the same frictional characteristics between bullet and barrel regardless of barrel, bullet, ambient temperature, or lube "phase". Modifying waxes and oils to give the congealed bore residue the same sort of friction characteristics when frozen at -10°F as when the barrel is warmer and the residue is the challenge. Many of us have observed another point of lube failure which causes gradual increase of group size over a long succession of shots, sometimes independent of barrel temperature, and sometimes directly related to it. This generally proved to have one or both of two root causes, one being excessive metal fouling accumulations in the barrel and the other simple lube viscosity breakdown which changed the friction characteristics of the bore as barrel temperature increased. Sometimes the viscosity breakdown seemed to cause the metal fouling, likely due to barrier and/or obturation failure and bullet abrasion and/or gas cutting, and is probably as often a bullet alloy problem as it is a failure of lube design. The temperature-related increase in group dispersion that can be described as "heat fade", is typically a simple viscosity failure of the lube changing the CORE as the barrel heats, either increasing or decreasing the net bullet/barrel friction beyond the optimum range for which the handloader developed the load. Heat fade is also characterized by the group dispersion returning to normal for a few shots when the barrel is allowed to cool and the shooting resumed. Some other things which I will argue are NOT failures directly attributable to a defect of lube formulation are throat leading, muzzle leading (running out of lube), and antimony wash. Throat leading is due to latent obturation, i.e. poor bullet fit, excessively fast-burning powder, bullet scraping the throat entrance, or excessive jump to the throat. Heavy leading toward the muzzle is often an alloy/powder mis-match causing loss of obturation far beyond what any lube can prevent. Hard bullets and fast powder are frequent offenders, as are soft bullets and too much velocity/pressure where no lube can prevent the abrasion and trailing edge leakage which results in gas cutting of the bullet and total loss of the lube's dynamic-film lubricating abilities. So-called "antimony wash" is something I generally do not find is an issue to accuracy because the metal dust becomes part of the slurry of lube and powder fouling and is often a very consistent fouling. That said, the presence of loose metal fouling in the bore may indicate that the system is operating under boundary conditions.
Finding solutions to the various problems often experienced with bullet lube proved to be a monumental task, since the solution to one problem often created others. To make the process a little easier, I chose to isolate a few of the lube's functions explore them to their logical end. In an effort to isolate the "fluid film" action of bullet lube, I shot bullets lubricated only with engine oil, finding it adequate for light to mid-range rifle loads as long as the bullet obturated the throat immediately and bore condition was mechanically very good. My impressions from those tests were that a "carrier" of sorts was necessary to hold the oil and also increase its viscosity at the start to help prevent throat leading. Obviously a carrier is needed to keep the lube in the grooves as well. Following one of Col. Harrison's experiments for the NRA, I progressed to metal-soap greases and finally, a multitude of very heavily thickened "brick" greases using virtually every kind of grease gellant in existence. Always the results were the same: When velocity was increased, leading began. Also, with sodium soap and aluminum, the gellent itself began to separate and deposit heavily in the bore when pressure and velocity was increased. Before the point of leading and soap deposits however, group accuracy was generally phenomenal. The oils and gellants alone proved insufficient to stop gas leaks and lube breakdown, so I went two different directions to see what was going on. The first direction was to add some solid material to act as a stop-leak. Finely-blended paper, baker's cake flour, corn starch, oil-field valve packing grease, etc. were all used in an attempt to stop the leakage, and to that end met with success but at the cost of creating a terrible issue of fouling. Any solids which are blown forward of the bullet when fired immediately become ironed on the bore just like atomized lead does, making heavy, lumpy deposits. The other direction was to gel the oil with wax and not include any metal salts to bind the mixture and no solid particles to act as stop-leak. Here I assumed I would find complete and easy success for everything up to medium-velocity loads since various oil and wax mixtures have been used successively for hundreds of years. However, when I tried several formulations of hard, high melt-point wax and light oils, the result as pressure/velocity was increased past just the mid-range point in rifles was complete failure to lubricate near the muzzle, and extreme cases of heat fade. Compared to a beeswax/Vaseline lubricant of similar room-temperature viscosity where the same failures did not happen until the extreme end of pressure and heat, the only conclusion I could draw was that wax adds a very important feature of gradual control of lube's viscosity drop. The brick grease lubes which were not thixotropic had issues due to not "melting", and the microwax/oil lubes that melted abruptly also were a problem, so further testing with wax/oil blends having the broadest possible spectrum of carbon chain length was done and the results were quite satisfactory. All of this basic work was essential to determining what sort of base ingredients and physical characteristics a lube needed, with the conclusion being a broad-spectrum branched and linear wax blend, thick and thin oils, "middle modifier" ingredients in the very soft wax/very heavy oil range was the best base formulation, and that metal soaps such as lithium and sodium would help control flow and bind the whole mixture together as required and allow a softer over-all formula for jettison purposes. Other additives such as molybdenum and zinc compounds and even graphite and various other extreme-pressure compounds can have their place in bullet lube, but the basic concept of a broad mixture of waxes, plasticized with a small amount of oil, has proven to be the essential base stock to build upon.
After establishing the base stock and determining that waxes, after all, will make an acceptable base for any temperature extreme, the only thing that remained, and still does remain as the principle topic of this thread, is perfecting the nuances of a lube to provide consistent performance no matter the circumstances. Maintaining CORE consistently to avoid the cold-bore flyers seems to be the biggest challenge of all, but careful blending of wax and oil with the idea of consistent friction no matter the temperature, and consistent purge shot to shot, will overcome that difficulty. Purge flyers can be mitigated by reducing or eliminating any "synthetic", or uniform-molecule content which creates plateaus in the melt phase, and by not having much thin oil in the mixture in the first place. Also, the addition of lithium or sodium soaps (particularly the latter) make an effective sponge of sorts which tends to mop the bore and control oil bleed under pressure so that not too much oil is left behind to cause purging. Certain synthetic oils with very high VI's are rather notorious for causing purge flyers and over-all poor accuracy due to inconsistent CORE. One remedy is to plasticize the base waxes with oils which thin sufficiently to evacuate consistently under any foreseeable shooting conditions, notably straight-chain paraffins with very low viscosity indeces. In order to combat heat fade, again the metal soaps are a great benefit, as is beeswax. The esters and solid alcohols in beeswax make an extremely durable film which is relatively consistent in friction under high pressure from solid to smoke point, and seems to maintain a lubricating film at high velocity and heat better than any single petroleum wax available. Lithium soap can and will fail badly in hot barrels because the molecules are very thin and relax easily in the heat, letting the oil go. Sodium soap has no practical upper temperature limit as a bullet lube ingredient, and also performs well in cold weather, likely due to having a molecule size approximately 100 times larger than lithium. The sodium soap has the drawback of leaving heavy, burned deposits in the bore if it is not fully gelled into a good wax matrix, but lithium brick grease will also leave deposits at high pressure without the presence of wax, so it isn't perfect in that regard either. In any case, the metal soaps are a great boon to maintaining CORE and extending temperature and velocity potential of a lube, with sodium having a distinct advantage against heat fade. Metal soaps also help raise the temperature point at which a wax/oil lube will weep oil, and enable the whole formula to work at higher temperatures and at higher rates of fire than the wax/oil base alone. Jettison issues can be tempered by adding paraffin and cutting back the beeswax component somewhat to reduce the adhesion of the lube to the bullet and also increase the rate of melting under pressure. Paraffin will turn to liquid almost instantly when pressurized to tens of thousands of pounds per square inch, which makes it a useful additive for adjusting the thixotropic nature of lube, and has the advantage of reduced friction when frozen compared to beeswax and microcrystalline petroleum waxes, but is not an extremely good stand-alone wax base except for all but mildest use.
Over the years, a picture of what ingredients worked well together and brought desirable characteristics to the lube at all ranges of the temperature spectrum (some of which work in pairs to cancel each other's weaknesses and bolster each other's strengths) began to emerge. Another thing which became clear to me was that there are an almost infinite number of ways to accomplish the ends with common ingredients, if one can only disseminate the variables and keep the ones with the characteristics needed for the job. I have, to date, been quite happy with one particular formulation which is more of a concept than a recipe, and is difficult to make a shopping list for. It goes like this:
One part firm wax base, being a blend of microcrystalline wax, beeswax, and macro or paraffin wax, with each of the petroleum waxes being comprised of a very full spectrum of carbon chain lengths ranging from about 18-20 molecules long to over 100.
One part sodium soap
One part petroleum jelly, preferably as un-refined as possible and not a reverse-engineered blend of a single fraction of wax and single fraction of paraffin oil as most drugstore USP petrolatums or name-brand "Vaseline" is currently.
Up to 2% highly-polar polyolester or natural castor bean oil for the actual "lube".
The broad-spectrum wax base provides both low and high temperature properties, with the paraffin working on both ends to make the solid lube more slick when frozen and also make the stronger, stiffer waxes liquify faster under pressure. The microwax and beeswax hold the mixture together and limit the viscosity drop at a useful point to provide the all-important film strength required by rifles at high-velocity and in hot weather or hot barrels. The sodium soap works in tandem with the beeswax and microwax like a fibrous micro-sponge to bind the ingredients physically and enhance the "stop-leak" effect of the lube, keeping it in the grooves and tolerating barrel imperfections better. The sodium soap also acts as a cleaning patch to keep CORE consistent in all shooting conditions, and enables the formula to be made quite soft for ease of application in lube-sizers without needing heat, and also performs the critical function of allowing an extreme-pressure rifle lube to still be made soft enough to easily and completely jettison from deep, square lube grooves at low velocity, such as when using Keith-style SWC bullets in a .38 Special revolver. The castor oil or ester oil acts an extreme-pressure lube which extends the useful high heat and/or high velocity range of the lube. The polarity of those oils works against the polarity of the metal soaps so the oils can let go from the wax/soap matrix when needed at the drive-side pressure point under high heat and pressure situations, but if the proportion is limited, this bleed tendency will not cause purging or CORE issues in cold weather or in low-pressure loads.
further editing notes.....
Antimony wash or abrasion leading with balanced loads: Add metal soaps, moly, graphite, increase MP of wax, add high VI lube component to extend dynamic film duration, add EP ingredients
First-shot POI, heat fade, and other CORE-related failures: Modify solid-state (cold barrel) friction...carnauba/microwax/beeswas for adding friction, paraffin wax for reducing it. Mid-point flow... modify base oil or middle modifier VI. Boundary end....add moly, castor, ester, increase metal soap content. Modify over-all viscosity (and friction) with micro/macro balanced blend on the top end or paraffin-oil plasticizer on the bottom end, extend/reduce the thixotropic effect with metal soaps or by altering wax structure.
Miscl comments: Esters and castor favor temperature extremes. Carnauba and lanolin gum up in the cold. Too many solids cause purging. Too much tacky wax (micro, carnauba) cause heat fade, also narrow-fraction microwaxes have very low VI/abrupt phase change and exacerbate heat fade. Discussion of hot storage/oil bleed/corrosion. Discussion of soft lube for all pressure levels, purpose to create recipe for which components are generally accessible, is relatively non-toxic, can be duplicated by relatively inexperienced lube cooks with common kitchen "tools", and which will serve the common goal of being temperature insensitive, tolerant of a multitude of lube groove styles, insensitive to bore finish quality, tough enough to satisfy extremely high-velocity rifle loads as well as very low-velocity loads, etc.....
Everyone else: Please contribute discussion, recipes, experiences with individual ingredients and their effects, etc.
Back, by popular request. Here goes...
A few years ago I set out to understand and solve a few problems common in one way or another to virtually every cast bullet lubricant that has so far been devised. The principle and common issue with typical lube formulations of the time was that each may work very well for specific purposes or a certain range of conditions, but none I tried provided acceptable results across the whole spectrum of realistic shooting or storage conditions. Sensitivity to extremes of ambient temperature, changes in temperature, high rates of fire, hot storage conditions, various bore finish qualities, and to various amounts applied to the bullet were the principle issues I sought to improve with the ultimate goal being to work out a recipe which would serve virtually anyone's needs. A few others joined the project and contributed immensely to the generation of hypothesis and devising tests to isolate and evaluate variables. The approach I took to solving the problems was to begin tabula rasa and through basic testing, acquire a better understanding of the mechanisms by which a cast bullet lubricant actually works. Once the functional mechanisms were established, we began to identify, define, and isolate the failure modes. Determining the cause and correction of these failure modes tended to happen simultaneously through experimentation as different ingredients and proportions were tested and results observed.
The basic function of a good cast bullet lubricant boils down to a few simple tasks. First and foremost it serves as a friction-reducing and wear-preventing barrier between bullet and barrel, though it was soon discovered in testing that the barrier can and does function in several distinct modes that can be described as deep-drawing lubricant, dynamic film lubricant, and boundary lubricant. The barrier itself between bullet and bore must provide consistent friction qualities throughout the extremes of operating ranges and lubricating modes if group consistency is to be maintained. Our friend Eutectic coined the acronym CORE, or Consistency Of Residuals Encountered, to describe this attribute that a lube and its residue must have both before, during, and after the shot is fired so that each bullet lands in the normal group, be it the first shot on a cold morning or the last from a hot, fast string of fire. I find the acronym CORE invaluable and will refer to it often. Bullet lube serves a very dynamic role within the gun and must transition from a near-solid with very high viscosity and film strength, to a pressurized liquid, to (in extreme cases of poor bore condition or very high sliding speed/pressure) a boundary lubricant where the solids within the compound act as a dry lube which will perform in the absence of the liquid film. In order to satisfy both CORE and wide temperature needs, the barrier which lube provides must have the same net friction characteristics under ALL of these conditions, at any point in the barrel, with any given load or gun combination in any weather. Another important task that a bullet lube performs is what Glen Fryxell has referred to as "ballistic stop-leak", put another way, a "dynamic obturation aid" which helps maintain an absolute seal between bullet and bore as the bullet encounters the virtually inevitable, minute surface and dimensional imperfections of the lands and grooves. At high velocity, the driving-side of the lands puts extreme pressure against the companion surface of the engraved bullet, resulting in accelerated friction, heat, and wear of the bullet metal, all which contribute to the bullet surface failing and ultimately, loss of obturation at the trailing side of the engraves. The barrier quality of the lube is critical to prevent this metal failure, but even if it succeeds in preventing drive-side wear, minute barrel imperfections can still cause the dynamic film to be lost on the other areas of the bullet/barrel interface if the lube viscosity becomes too low for the pressure and degree of barrel imperfection. Developing lube chemistry that will allow a certain necessary viscosity reduction during the shot for dynamic film lubrication, yet control viscosity breakdown to prevent loss of obturation in rough barrels proved essential to achieving a sturdy, multipurpose lube and is still one of the biggest challenges for any recipe. The final principle concept of lube function has been described by Fiver, and is the only part involving exterior ballistics: Lube remaining in the grooves as the bullet exits the muzzle should "either all stay or go" so that it doesn't depart erratically along the path to the target and cause the bullet to veer. Much experimentation revealed that the "all go" is much easier to achieve with a universal lube than "all stay", so my efforts focused on achieving immediate jettison reliably under just about any condition by manipulating the physical characteristics of "tack" or adhesion, plasticity, and thixotropy. So, in a nutshell, the principle functions of bullet lube boil down to keeping the bullet's surface from contacting the barrel steel, maintaining a positive seal (obturation) between the bullet and barrel, and then when it's job is done at the muzzle, getting off the bullet and out of the way as soon as possible so as not to become a bullet balance liability later.
Having conceptualized the function of bullet lubricant, the next task was to determine how the problems we observed on targets or in the guns related to failures of function, and which function to address with a solution. The problem of cyclic flyers can be loosely attributed to "lube purge", or a gradual accumulation of deposits in the bore which the succeeding bullets "run over" without apparent difficulty until the whole mess goes out at once with one shot, causing a flyer, and the process repeats. I don't claim to understand the mechanisms of this phenomena thoroughly, and like many things shooting-related can only be observed through secondary indicators, but at this point I have concluded that lube recipes which leave more lube or components of lube behind than is purged each shot because the oil in the formula has too high of a viscosity index and doesn't thin enough to evacuate predictably are the main cause of this. Cold-barrel flyers are another burr under the cast-bullet shooter's saddle, particularly with regard to hunting applications where the first shot point of impact needs to be absolutely consistent and predictable. Correcting the cold-barrel point of impact shift is almost entirely a function of effectively managing CORE by creating a lube that effectively maintains the same frictional characteristics between bullet and barrel regardless of barrel, bullet, ambient temperature, or lube "phase". Modifying waxes and oils to give the congealed bore residue the same sort of friction characteristics when frozen at -10°F as when the barrel is warmer and the residue is the challenge. Many of us have observed another point of lube failure which causes gradual increase of group size over a long succession of shots, sometimes independent of barrel temperature, and sometimes directly related to it. This generally proved to have one or both of two root causes, one being excessive metal fouling accumulations in the barrel and the other simple lube viscosity breakdown which changed the friction characteristics of the bore as barrel temperature increased. Sometimes the viscosity breakdown seemed to cause the metal fouling, likely due to barrier and/or obturation failure and bullet abrasion and/or gas cutting, and is probably as often a bullet alloy problem as it is a failure of lube design. The temperature-related increase in group dispersion that can be described as "heat fade", is typically a simple viscosity failure of the lube changing the CORE as the barrel heats, either increasing or decreasing the net bullet/barrel friction beyond the optimum range for which the handloader developed the load. Heat fade is also characterized by the group dispersion returning to normal for a few shots when the barrel is allowed to cool and the shooting resumed. Some other things which I will argue are NOT failures directly attributable to a defect of lube formulation are throat leading, muzzle leading (running out of lube), and antimony wash. Throat leading is due to latent obturation, i.e. poor bullet fit, excessively fast-burning powder, bullet scraping the throat entrance, or excessive jump to the throat. Heavy leading toward the muzzle is often an alloy/powder mis-match causing loss of obturation far beyond what any lube can prevent. Hard bullets and fast powder are frequent offenders, as are soft bullets and too much velocity/pressure where no lube can prevent the abrasion and trailing edge leakage which results in gas cutting of the bullet and total loss of the lube's dynamic-film lubricating abilities. So-called "antimony wash" is something I generally do not find is an issue to accuracy because the metal dust becomes part of the slurry of lube and powder fouling and is often a very consistent fouling. That said, the presence of loose metal fouling in the bore may indicate that the system is operating under boundary conditions.
Finding solutions to the various problems often experienced with bullet lube proved to be a monumental task, since the solution to one problem often created others. To make the process a little easier, I chose to isolate a few of the lube's functions explore them to their logical end. In an effort to isolate the "fluid film" action of bullet lube, I shot bullets lubricated only with engine oil, finding it adequate for light to mid-range rifle loads as long as the bullet obturated the throat immediately and bore condition was mechanically very good. My impressions from those tests were that a "carrier" of sorts was necessary to hold the oil and also increase its viscosity at the start to help prevent throat leading. Obviously a carrier is needed to keep the lube in the grooves as well. Following one of Col. Harrison's experiments for the NRA, I progressed to metal-soap greases and finally, a multitude of very heavily thickened "brick" greases using virtually every kind of grease gellant in existence. Always the results were the same: When velocity was increased, leading began. Also, with sodium soap and aluminum, the gellent itself began to separate and deposit heavily in the bore when pressure and velocity was increased. Before the point of leading and soap deposits however, group accuracy was generally phenomenal. The oils and gellants alone proved insufficient to stop gas leaks and lube breakdown, so I went two different directions to see what was going on. The first direction was to add some solid material to act as a stop-leak. Finely-blended paper, baker's cake flour, corn starch, oil-field valve packing grease, etc. were all used in an attempt to stop the leakage, and to that end met with success but at the cost of creating a terrible issue of fouling. Any solids which are blown forward of the bullet when fired immediately become ironed on the bore just like atomized lead does, making heavy, lumpy deposits. The other direction was to gel the oil with wax and not include any metal salts to bind the mixture and no solid particles to act as stop-leak. Here I assumed I would find complete and easy success for everything up to medium-velocity loads since various oil and wax mixtures have been used successively for hundreds of years. However, when I tried several formulations of hard, high melt-point wax and light oils, the result as pressure/velocity was increased past just the mid-range point in rifles was complete failure to lubricate near the muzzle, and extreme cases of heat fade. Compared to a beeswax/Vaseline lubricant of similar room-temperature viscosity where the same failures did not happen until the extreme end of pressure and heat, the only conclusion I could draw was that wax adds a very important feature of gradual control of lube's viscosity drop. The brick grease lubes which were not thixotropic had issues due to not "melting", and the microwax/oil lubes that melted abruptly also were a problem, so further testing with wax/oil blends having the broadest possible spectrum of carbon chain length was done and the results were quite satisfactory. All of this basic work was essential to determining what sort of base ingredients and physical characteristics a lube needed, with the conclusion being a broad-spectrum branched and linear wax blend, thick and thin oils, "middle modifier" ingredients in the very soft wax/very heavy oil range was the best base formulation, and that metal soaps such as lithium and sodium would help control flow and bind the whole mixture together as required and allow a softer over-all formula for jettison purposes. Other additives such as molybdenum and zinc compounds and even graphite and various other extreme-pressure compounds can have their place in bullet lube, but the basic concept of a broad mixture of waxes, plasticized with a small amount of oil, has proven to be the essential base stock to build upon.
After establishing the base stock and determining that waxes, after all, will make an acceptable base for any temperature extreme, the only thing that remained, and still does remain as the principle topic of this thread, is perfecting the nuances of a lube to provide consistent performance no matter the circumstances. Maintaining CORE consistently to avoid the cold-bore flyers seems to be the biggest challenge of all, but careful blending of wax and oil with the idea of consistent friction no matter the temperature, and consistent purge shot to shot, will overcome that difficulty. Purge flyers can be mitigated by reducing or eliminating any "synthetic", or uniform-molecule content which creates plateaus in the melt phase, and by not having much thin oil in the mixture in the first place. Also, the addition of lithium or sodium soaps (particularly the latter) make an effective sponge of sorts which tends to mop the bore and control oil bleed under pressure so that not too much oil is left behind to cause purging. Certain synthetic oils with very high VI's are rather notorious for causing purge flyers and over-all poor accuracy due to inconsistent CORE. One remedy is to plasticize the base waxes with oils which thin sufficiently to evacuate consistently under any foreseeable shooting conditions, notably straight-chain paraffins with very low viscosity indeces. In order to combat heat fade, again the metal soaps are a great benefit, as is beeswax. The esters and solid alcohols in beeswax make an extremely durable film which is relatively consistent in friction under high pressure from solid to smoke point, and seems to maintain a lubricating film at high velocity and heat better than any single petroleum wax available. Lithium soap can and will fail badly in hot barrels because the molecules are very thin and relax easily in the heat, letting the oil go. Sodium soap has no practical upper temperature limit as a bullet lube ingredient, and also performs well in cold weather, likely due to having a molecule size approximately 100 times larger than lithium. The sodium soap has the drawback of leaving heavy, burned deposits in the bore if it is not fully gelled into a good wax matrix, but lithium brick grease will also leave deposits at high pressure without the presence of wax, so it isn't perfect in that regard either. In any case, the metal soaps are a great boon to maintaining CORE and extending temperature and velocity potential of a lube, with sodium having a distinct advantage against heat fade. Metal soaps also help raise the temperature point at which a wax/oil lube will weep oil, and enable the whole formula to work at higher temperatures and at higher rates of fire than the wax/oil base alone. Jettison issues can be tempered by adding paraffin and cutting back the beeswax component somewhat to reduce the adhesion of the lube to the bullet and also increase the rate of melting under pressure. Paraffin will turn to liquid almost instantly when pressurized to tens of thousands of pounds per square inch, which makes it a useful additive for adjusting the thixotropic nature of lube, and has the advantage of reduced friction when frozen compared to beeswax and microcrystalline petroleum waxes, but is not an extremely good stand-alone wax base except for all but mildest use.
Over the years, a picture of what ingredients worked well together and brought desirable characteristics to the lube at all ranges of the temperature spectrum (some of which work in pairs to cancel each other's weaknesses and bolster each other's strengths) began to emerge. Another thing which became clear to me was that there are an almost infinite number of ways to accomplish the ends with common ingredients, if one can only disseminate the variables and keep the ones with the characteristics needed for the job. I have, to date, been quite happy with one particular formulation which is more of a concept than a recipe, and is difficult to make a shopping list for. It goes like this:
One part firm wax base, being a blend of microcrystalline wax, beeswax, and macro or paraffin wax, with each of the petroleum waxes being comprised of a very full spectrum of carbon chain lengths ranging from about 18-20 molecules long to over 100.
One part sodium soap
One part petroleum jelly, preferably as un-refined as possible and not a reverse-engineered blend of a single fraction of wax and single fraction of paraffin oil as most drugstore USP petrolatums or name-brand "Vaseline" is currently.
Up to 2% highly-polar polyolester or natural castor bean oil for the actual "lube".
The broad-spectrum wax base provides both low and high temperature properties, with the paraffin working on both ends to make the solid lube more slick when frozen and also make the stronger, stiffer waxes liquify faster under pressure. The microwax and beeswax hold the mixture together and limit the viscosity drop at a useful point to provide the all-important film strength required by rifles at high-velocity and in hot weather or hot barrels. The sodium soap works in tandem with the beeswax and microwax like a fibrous micro-sponge to bind the ingredients physically and enhance the "stop-leak" effect of the lube, keeping it in the grooves and tolerating barrel imperfections better. The sodium soap also acts as a cleaning patch to keep CORE consistent in all shooting conditions, and enables the formula to be made quite soft for ease of application in lube-sizers without needing heat, and also performs the critical function of allowing an extreme-pressure rifle lube to still be made soft enough to easily and completely jettison from deep, square lube grooves at low velocity, such as when using Keith-style SWC bullets in a .38 Special revolver. The castor oil or ester oil acts an extreme-pressure lube which extends the useful high heat and/or high velocity range of the lube. The polarity of those oils works against the polarity of the metal soaps so the oils can let go from the wax/soap matrix when needed at the drive-side pressure point under high heat and pressure situations, but if the proportion is limited, this bleed tendency will not cause purging or CORE issues in cold weather or in low-pressure loads.
further editing notes.....
Antimony wash or abrasion leading with balanced loads: Add metal soaps, moly, graphite, increase MP of wax, add high VI lube component to extend dynamic film duration, add EP ingredients
First-shot POI, heat fade, and other CORE-related failures: Modify solid-state (cold barrel) friction...carnauba/microwax/beeswas for adding friction, paraffin wax for reducing it. Mid-point flow... modify base oil or middle modifier VI. Boundary end....add moly, castor, ester, increase metal soap content. Modify over-all viscosity (and friction) with micro/macro balanced blend on the top end or paraffin-oil plasticizer on the bottom end, extend/reduce the thixotropic effect with metal soaps or by altering wax structure.
Miscl comments: Esters and castor favor temperature extremes. Carnauba and lanolin gum up in the cold. Too many solids cause purging. Too much tacky wax (micro, carnauba) cause heat fade, also narrow-fraction microwaxes have very low VI/abrupt phase change and exacerbate heat fade. Discussion of hot storage/oil bleed/corrosion. Discussion of soft lube for all pressure levels, purpose to create recipe for which components are generally accessible, is relatively non-toxic, can be duplicated by relatively inexperienced lube cooks with common kitchen "tools", and which will serve the common goal of being temperature insensitive, tolerant of a multitude of lube groove styles, insensitive to bore finish quality, tough enough to satisfy extremely high-velocity rifle loads as well as very low-velocity loads, etc.....
Everyone else: Please contribute discussion, recipes, experiences with individual ingredients and their effects, etc.
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