Advice: Lead alloy and bhn
- Thread starter burbank.jung
- Start date
Bret4207
At the casting bench in the sky. RIP Bret.
Yupper, times ARE a changin'!!! I had to hunt to find some plain old 50/50 solder to do a job here recently. I can find almost pure tin solder, but 50/50 is a rough one. I kinda doubt the sweated joints in the millions of miles of copper piping in this nation are responsible for the idiocy we see around us!
I still have a mess of ingots and pails of old WW. If the day comes when I've shot it all up, assuming we have any guns whatsoever in the future, I'll likely order from a commercial supplier rather than try and hunt up a local supply. Actually, there was a lot of lead mining in this area, but the smelting process to get the pure lead appears rather involved. I was hoping it was as simple as just building a big fire under a pile of Galena bearing rock and the lead would run out. Not so it seems.
I still have a mess of ingots and pails of old WW. If the day comes when I've shot it all up, assuming we have any guns whatsoever in the future, I'll likely order from a commercial supplier rather than try and hunt up a local supply. Actually, there was a lot of lead mining in this area, but the smelting process to get the pure lead appears rather involved. I was hoping it was as simple as just building a big fire under a pile of Galena bearing rock and the lead would run out. Not so it seems.
Winelover
North Central Arkansas
50-50 has been replaced by lead free 95-5 ................probably over 20 years ago. I still have a 20# spool of it in my tool box, left over from my plumbing/pipefitting days.
I use a full one pound spool of 95-5 to mix with 20 pounds of pure to get my version of 20-1 alloy. Much easier than doing the math for 50-50 or any of the other variations.
I use a full one pound spool of 95-5 to mix with 20 pounds of pure to get my version of 20-1 alloy. Much easier than doing the math for 50-50 or any of the other variations.
burbank.jung
Active Member
Huh?? If I take a bullet dropped from the mold, pick it up with a tweezer and dip the base and shaft into cold water to temper it, the base will be softer than the tip?
burbank.jung
Active Member
Here is the best group I shot with 40-160 Mihec cast bullets today. Sorry stat lovers but I don't have many CCI primers left so the number of testloads were limited. Does the quality of a mold make a more accurate bullet? For my first time shooting Mihec cast bullets, they're grouping better than my Lees.
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Bret4207
At the casting bench in the sky. RIP Bret.
Read post 49.
Bret4207
At the casting bench in the sky. RIP Bret.
Different mould, different fit. It's not the quality of the mould, although better quality is always good. It's the diameter, shape and weight and all the other tiny variables that make a difference in how the bullet fits in the case and, more importantly, how the bullet fits after the primer is struck and pressure starts doing it's thing. Static fit, dynamic fit.
In all seriousness, I can't stress this enough- FIT is King in this game. Everything else that brings you success is related to the fit of the bullet as it travels up the barrel. Lead alloys are so soft compared to jacket materials that it's simply foolish to think you can make a lead alloy bullet that even begins to approach the strength they have. You have to do the best you can to get a bullet that survives the trip up the barrel in the best form possible, and that form varies with what the particular gun wants. Change one element of the dozens involved and it can go from good to bad or bad to good or not change at all.
Art and science, right?
fiver
Well-Known Member
touching on what Bret said some.
when you move the bullet you move the bullet in more than one direction.
if you follow the it's gotta be huge to work thing your also changing the length of the bullet when you shove it in the pipe.
think about sizing a 45 cal bullet down to 44.
the weight doesn't change, but it sure gets a lot longer. that's partly what happens in the barrel.
now throw in the metal being moved by the lands, it has to go somewhere also.
how the bullet handles that is a good portion of the design, like where the grooves are cut and the angles of those grooves as well as the base shape.
there's more to it and as the pressure and acceleration forces go up things change even more, but you get the idea.
it's been a while since i've had to think this through all the way and put it all into an actual design, but it can get complicated pretty quickly when your trying to balance the COG with groove placement and nose design.
when you move the bullet you move the bullet in more than one direction.
if you follow the it's gotta be huge to work thing your also changing the length of the bullet when you shove it in the pipe.
think about sizing a 45 cal bullet down to 44.
the weight doesn't change, but it sure gets a lot longer. that's partly what happens in the barrel.
now throw in the metal being moved by the lands, it has to go somewhere also.
how the bullet handles that is a good portion of the design, like where the grooves are cut and the angles of those grooves as well as the base shape.
there's more to it and as the pressure and acceleration forces go up things change even more, but you get the idea.
it's been a while since i've had to think this through all the way and put it all into an actual design, but it can get complicated pretty quickly when your trying to balance the COG with groove placement and nose design.
Bret4207
At the casting bench in the sky. RIP Bret.
Good points Fiver. I've said "fatter is better" in the past, but there are clearly limits to that and I meant it more as a general theory than a specific recommendation. Half a thou bigger is almost always better than half a thou smaller unless you're trying to mash that bullet into putty in order to get it to fit. Balance, finding the right balance is the key I suppose, and that changes with very gun/bullet/powder/etc you change.
fiver
Well-Known Member
Balance is the key
like you say about fitment is the real deal.
but the actual design allows the fitment to flow with the least amount of damage to the bullet.
the old days... it was all antimony alloy bullets for rifles because everyone was trying to fight the nose slump of those long bore riders.
now days.... more fluid alloys, and bullet shapes that don't ride the lands so much, but take them up gradually into the body and the grooves are placed/angled so the alloy can flow into them without really disrupting the lube seal.
Me and Ian have had,,, jeez i dunno 75-300 PM's discussing just the wall angle on a lube groove, and at least 50 more on lube volume or number of grooves.
plus length of the gas check shank for taking up that last bit of displaced alloy.
we don't totally agree on some of it, but we do agree it has to be dealt with in the most efficient and least disruptive way.
one thing i can say with a little bit of certainty, is that there is more than one way to get there but some areas of the bullet [and their angles] matter a lot more than others to get you past the first 1/2 inch or so of travel.
like you say about fitment is the real deal.
but the actual design allows the fitment to flow with the least amount of damage to the bullet.
the old days... it was all antimony alloy bullets for rifles because everyone was trying to fight the nose slump of those long bore riders.
now days.... more fluid alloys, and bullet shapes that don't ride the lands so much, but take them up gradually into the body and the grooves are placed/angled so the alloy can flow into them without really disrupting the lube seal.
Me and Ian have had,,, jeez i dunno 75-300 PM's discussing just the wall angle on a lube groove, and at least 50 more on lube volume or number of grooves.
plus length of the gas check shank for taking up that last bit of displaced alloy.
we don't totally agree on some of it, but we do agree it has to be dealt with in the most efficient and least disruptive way.
one thing i can say with a little bit of certainty, is that there is more than one way to get there but some areas of the bullet [and their angles] matter a lot more than others to get you past the first 1/2 inch or so of travel.
Ian
Notorious member
Yep, very much so. This is the essence of "dynamic fit", but the topics of just how the metal can move, why, and what we really want it to do has inconvenienced more electrons in our heads and internet lines than most would imagine.
The trick to understanding this is that the forces don't turn the whole bullet to putty, don't turn it to putty all at once, and turn it to varying degrees of putty in each place at different times along the way if at all. Most of the dynamic shape change is over in the first half inch of bullet travel, but that period is absolutely critical and doesn't necessarily imply an exact, fully-supported glove-fit at any point in the firing sequence. Some parts of the bullet change shape due to gas pressure fronts and jets, some by static inertia, and others from being influenced by the barrel steel. The contituents of the alloy influence bullet dynamics at least as much as does the shape we make the bullet to start with and the components we choose to punt it through the pipe.
Yep again. The least amount of non-repeatable, non-concentric damage. However, some of my best high-velocity rifle loads made nearly a half point of BC change to the bullet inside the gun, so the shape-shifting can be large as long as it happens the same way every time.
I never would have believed that 165-A would have matched what a wiggly self-aligning bullet with 30 times the lube volume did until you showed me. You had to do different stuff with alloy to make it work, but both designs liked the same basic lube consistency at high speed which was an "Aha!" moment for me.
Definitely more than one way to fit a bullet to a rifle even at same weights, pressures, and speeds but some things like pressure curve, sized diameter, and seating depth will need to be worked around a little to make a given method come together. There are also lots of ways that just won't work no matter what.
Burbank, it all boils down to how successful you are at making the bullet you have fit the gun you have AFTER the primer goes off by doing the right stuff BEFORE the primer goes off. I.E. static and dynamic fit and handloading techniques.
I really don't care much for two-diameter bullets for most applications because most guns don't have two distinct diameters to fit them to in the first place and less so after they've been shot a bit and worn. However, there are exceptions and two that come to mind from my gun safe are both large revolver cartridge chamberings with torpedo-shaped throats that go halfway to the muzzle. The best options I found for them have been paper-patched bullets wet-wrapped and sized for a snug fit in the biggest part of the throats, and heavy-for-caliber two-diameter bullets with as much bore-riding nose length as I could squeeze into the rifling and the back end as fat as would chamber, but with a little gap between the sizes at the back of the throat so the bearing part if the bullet could get a little free run at the barrel without getting crooked (same as how Fiver fit Tomme's Accurate 165-A in the .308). As long as there is enough twist to stabilize the extra-long bullet so fitted, it worked extremely well. Think about what a paper-patched bullet with a tight static fit to the throat in all directions and a Barlow bullet tightly fitted radially but not longitudinally have in common and it may provide a clue to how to proceed with this stubborn CVA.
Bret4207
At the casting bench in the sky. RIP Bret.
2 great posts Fiver and Ian! Thanks! You put into words a lot of whats been rattling around in my head for 20 years! Picturing the bullet in the throat, just starting it's movement, unequal displacement/slump as the pressure affects it! You filled in a couple of shady spots for me. I hadn't considered things like wall angle on a lube groove or lube consistency (is that related to hydraulic support of the alloy under pressure?). Now I have more new questions!
Thing is, will people read those posts and get that lightbulb moment that it's not just about a Bhn? Doesn't look that way so far!
Thing is, will people read those posts and get that lightbulb moment that it's not just about a Bhn? Doesn't look that way so far!
fiver
Well-Known Member
strength doesn't relate to BHN.
think about it like this.
antimony adds BHN, right? we all know that.
but most don't know those dead soft,, swaged and knurled dead soft [hollow base wad cutters] bullets have 3-5% antimony in them.
how can that be?
they suck,,, they are so soft you can't push them past about 800 fps without stripping the rifling and leaving a big mess behind.
5% antimony you say????
no way!!!
the BHN would be 15 or 16.
well way, that's how it is.
okay??? [ Fiver your N IDJIT] but go on...L not O.L. and eye rolling.
stay with me here.
remember the part where i said it was swaged?
under stress and pressure antimony breaks down, this allows the lead around it to slide and glide over itself even easier than it would without the internal crystals breaking down.
[think hitting a bent nail, it's already bent the structure is broken, it just bends easier the second time]
now.
this is one of my theories.
when you shove the bullet into the barrel you are actually swaging it only in an open tube instead of against the back side of a die.
there is still air resistance to push against, but the bullet trying not to move and the rising pressure pushing against it is partially swaging some parts and pieces of the bullet.
so the putty thing isn't too far off because you ARE smushing the bullet ahead and forcing parts of it to move and glide.
the antimony in those areas is breaking down and allowing the bullet alloy to moove even easier.
you gotta use enough stuff in the alloy to combat that, you can also help yourself out by top pressure management, and acceleration velocity.
more harder [antimony] isn't the answer it can actually contribute to the problem.
think about it like this.
antimony adds BHN, right? we all know that.
but most don't know those dead soft,, swaged and knurled dead soft [hollow base wad cutters] bullets have 3-5% antimony in them.
how can that be?
they suck,,, they are so soft you can't push them past about 800 fps without stripping the rifling and leaving a big mess behind.
5% antimony you say????
no way!!!
the BHN would be 15 or 16.
well way, that's how it is.
okay??? [ Fiver your N IDJIT] but go on...L not O.L. and eye rolling.
stay with me here.
remember the part where i said it was swaged?
under stress and pressure antimony breaks down, this allows the lead around it to slide and glide over itself even easier than it would without the internal crystals breaking down.
[think hitting a bent nail, it's already bent the structure is broken, it just bends easier the second time]
now.
this is one of my theories.
when you shove the bullet into the barrel you are actually swaging it only in an open tube instead of against the back side of a die.
there is still air resistance to push against, but the bullet trying not to move and the rising pressure pushing against it is partially swaging some parts and pieces of the bullet.
so the putty thing isn't too far off because you ARE smushing the bullet ahead and forcing parts of it to move and glide.
the antimony in those areas is breaking down and allowing the bullet alloy to moove even easier.
you gotta use enough stuff in the alloy to combat that, you can also help yourself out by top pressure management, and acceleration velocity.
more harder [antimony] isn't the answer it can actually contribute to the problem.
Ian
Notorious member
Sometimes that crush and breakdown is what you want. In all cases, the rifling lands make that crush inevitable and in the spot you least want strength loss a foot or two up the barrel. We may want the shoulder of the bullet to crush and glide into the bore without very high resistance because the higher the resistance, the higher the pressure on the base needed to overcome it and the faster the rate of powder burn/pressure rise occurs, which in turn puts a lot more smushing power on the bullet base and can make it fully rivet to the confines of the chamber neck inside the case. Base riveting is something which almost never happens in a controlled, consistent fashion while maintaining consistency of form with what the front end of the bullet is doing. It's like balancing a stack of plates on a pogo stick and then launching the whole mess up into the air: The forces will never be in line enough for the stick and stack to come back down again in perfect alignment.
Sometimes we want to do our damnedest to prevent shoulder crush, like in a revolver, but that's a whole 'nuther thing. A balancing dose of tin will make a strong intermetallic lattice which is malleable but not thixotropic; in other words doesn't go to putty once crushed but merely squishes as much as it needs to without becoming weaker in the process.
Trying to fit a bullet to a .308 Winchester throat compared to a .30-'06 throat (or the opposite) is a nightmare. If you a tough, close-fitting bullet into an '06, it takes a lot of extra pressure on the base to force the bullet through and does murder to the base geometry. The harder the bullet, the worse the outcome. There's a balance where a relatively malleable and crushable bullet will deform plenty while engraving but in places where it doesn't destroy the bullet's balance and form. The challenge with the '06 is the neck clearance is large, the throat entrance is large, and the bore is comparatively small. The bullet needs to be fitted so it doesn't rattle around like a BB in a boxcar and hit the throat all crooked, but it also has to get squeezed a lot to accomplish this. The neck is long, bullets are typically heavier than .308, and there's a LOT of bearing length that needs to be fat and needs to get drawn through the throat funnel. Much to go wrong. The .308 has a parallel freebore and two smaller transition tapers, so it is possible to make a tougher bullet that only has to go from .310 to .308/300 instead of .312 to .308/300 and the neck is so short that the typical bearing length is short and the throat itself can be used to guide the bullet from the middle and front instead of relying on support from both ends, effectively eliminating the need to fill the case neck to the chamber walls for support at the back. This eliminates quite a few problems at high velocity, particularly the issue of a crushed/weak alloy having to contend with high twist forces and abrasion further on up the pipe. Can't go TOO tough, though, because as pressure drops off that relax point happens and lube blowout/gas cutting/muzzle end leading can occur, which isn't good for accuracy. Using extremely hard alloy here also ruins things at high velocity for the same reason (loss of obturation) and has the added problem of being very brittle and easily abraded by the driving side of the lands.
Doing a little actual math reveals some interesting things. Using the BHN formula and Quickload models, it is possible to develop an approximate and somewhat oversimplified slow-motion movie of what is happening at launch. Take water/quenched 2.5% antimony/.5% tin alloy with enough trace other stuff so it precipitation hardens to about 20 BHN over a month. 20 BHN can take about 29,000 PSI of force before it begins to permanently deform. Now, take a 56,000 PSI PEAK pressure .308 load using Reloder 7, a fairly quick rifle powder for high-velocity applications and a charge that develops in the 90%+ of the maximum allowable peak pressure. Recipe for failure, right? Nope. The bullet is moving, and the front end has begun to squeeze through the throat already and the back end has moved a third of an inch before pressure reaches the point on the base where it permanently deforms. Guess what? By then, the front of the gas check is entering the throat the most of the bullet is quite safely inside the throat and barrel with full contact everywhere except for some stripes near the front of the nose in the groove area, the lube groove spaces, and the gas check shank which is centered at the throat entrance by the harder gas check anyway. After that, add as much pressure as you like and it isn't going to harm the bullet because it has nowhere to go but straight ahead. This situation can be made even better by selecting a bullet which starts out being able to align to center as it moves forward, BUT has some space here and there so the contact and resistance occurs incrementally from near zero on up instead of starting against the load of being a match fit with no jump. Also consider that the bullet at 1/3" travel is moving at an instantaneous velocity of 350 FPS and accelerating rapidly, so it has INERTIA to carry it through the highest point of engraving resistance...and that force is subtracted from rather than added to the force that needs to be applied to the bullet's base by expanding powder gas to cram the bullet into the throat. This means that the alloy will crush sooner and more easily on the front than the back and will allow the base of the bullet to deform essentially none due to gas pressure, i.e. NO RIVETING while the front and middle squeeze down several thousandths and in some cases elongates the bullet from the back to the front. Also, remember this is a bullet made of 10.5 BHN putty which has been artificially reinforced by quenching and precipitation hardening to nearly double the test number in "hardness", and the front goes from 29,000 PSI strong to more like 15,000 PSI strong as soon as the shoulder and front bands begin to deform into the throat. Yet, we don't crush the back end so the alloy is STILL 29,000 PSI strong. All this lets the bullet engrave easily without distorting the back, and doing that gets the bullet straight into the bore without bending, riveting, or collapsing at its grooves. The only hurdle remaining is keeping obturation up with weakened driving surfaces at 2,400 fps and 180,000 RPM a couple inches from the end of the muzzle. Remember, crushed alloy gets instantly hot, add barrel friction and a barrel that's hot to begin with, and the fact that lead alloy loses strength at a rate that's the square of temperature, so the bullet might really be something like 8 bhn at the drive side of the bands, at the muzzle. This still works though because if you calculate through F.W. Mann's exhaustive formula the pressure on the engraving/torsional bearing area of a bullet like the MP-30-180 Silhouette for a .004" land height and four grooves, the pressure is only about 10,000 PSI (a lot less than that many pounds on a lot less than a square inch, actually, but the same "per"), and the bullet metal at BHN 8 will take over 11,000 PSI of force to deform it. If your lube and alloy blend keeps the abrasion down, you can JUST pull off the launch without losing obturation and getting the accuracy-destroying drive side wear, loss of obturation (leaks), lube blowout, leading, and a damaged bullet which won't fly straight.
Now, try the same thing with 22 BHN Linotype alloy and see what you get. Spoiler alert, it's not even minute of berm accurate and will teach you right quick that there's more use for a Chore Boy pad than cleaning stuck grease out of pots and pans.
Further, try NOT water-quenching that alloy and instead add a .001"-thick, 30 BHN, self-lubricating, heat insulating jacket. Instant good results. Why? The slicker than lead coating reduces engraving force even more than a stiff but crushable alloy alone, so the 15,000 PSI strength of the air-cooled, 10.5 BHN base is enough to hold the base in form until the gas check goes in the throat and also adds surface strength and heat insulation to keep the alloy strong while it shoulders the rifling twist and hauls ass out of the muzzle without leaking or getting washed out.
I forgot where I was going with all that, but maybe if anyone actually read all that it will at least make what some of what Fiver wrote make more sense.
Sometimes we want to do our damnedest to prevent shoulder crush, like in a revolver, but that's a whole 'nuther thing. A balancing dose of tin will make a strong intermetallic lattice which is malleable but not thixotropic; in other words doesn't go to putty once crushed but merely squishes as much as it needs to without becoming weaker in the process.
Trying to fit a bullet to a .308 Winchester throat compared to a .30-'06 throat (or the opposite) is a nightmare. If you a tough, close-fitting bullet into an '06, it takes a lot of extra pressure on the base to force the bullet through and does murder to the base geometry. The harder the bullet, the worse the outcome. There's a balance where a relatively malleable and crushable bullet will deform plenty while engraving but in places where it doesn't destroy the bullet's balance and form. The challenge with the '06 is the neck clearance is large, the throat entrance is large, and the bore is comparatively small. The bullet needs to be fitted so it doesn't rattle around like a BB in a boxcar and hit the throat all crooked, but it also has to get squeezed a lot to accomplish this. The neck is long, bullets are typically heavier than .308, and there's a LOT of bearing length that needs to be fat and needs to get drawn through the throat funnel. Much to go wrong. The .308 has a parallel freebore and two smaller transition tapers, so it is possible to make a tougher bullet that only has to go from .310 to .308/300 instead of .312 to .308/300 and the neck is so short that the typical bearing length is short and the throat itself can be used to guide the bullet from the middle and front instead of relying on support from both ends, effectively eliminating the need to fill the case neck to the chamber walls for support at the back. This eliminates quite a few problems at high velocity, particularly the issue of a crushed/weak alloy having to contend with high twist forces and abrasion further on up the pipe. Can't go TOO tough, though, because as pressure drops off that relax point happens and lube blowout/gas cutting/muzzle end leading can occur, which isn't good for accuracy. Using extremely hard alloy here also ruins things at high velocity for the same reason (loss of obturation) and has the added problem of being very brittle and easily abraded by the driving side of the lands.
Doing a little actual math reveals some interesting things. Using the BHN formula and Quickload models, it is possible to develop an approximate and somewhat oversimplified slow-motion movie of what is happening at launch. Take water/quenched 2.5% antimony/.5% tin alloy with enough trace other stuff so it precipitation hardens to about 20 BHN over a month. 20 BHN can take about 29,000 PSI of force before it begins to permanently deform. Now, take a 56,000 PSI PEAK pressure .308 load using Reloder 7, a fairly quick rifle powder for high-velocity applications and a charge that develops in the 90%+ of the maximum allowable peak pressure. Recipe for failure, right? Nope. The bullet is moving, and the front end has begun to squeeze through the throat already and the back end has moved a third of an inch before pressure reaches the point on the base where it permanently deforms. Guess what? By then, the front of the gas check is entering the throat the most of the bullet is quite safely inside the throat and barrel with full contact everywhere except for some stripes near the front of the nose in the groove area, the lube groove spaces, and the gas check shank which is centered at the throat entrance by the harder gas check anyway. After that, add as much pressure as you like and it isn't going to harm the bullet because it has nowhere to go but straight ahead. This situation can be made even better by selecting a bullet which starts out being able to align to center as it moves forward, BUT has some space here and there so the contact and resistance occurs incrementally from near zero on up instead of starting against the load of being a match fit with no jump. Also consider that the bullet at 1/3" travel is moving at an instantaneous velocity of 350 FPS and accelerating rapidly, so it has INERTIA to carry it through the highest point of engraving resistance...and that force is subtracted from rather than added to the force that needs to be applied to the bullet's base by expanding powder gas to cram the bullet into the throat. This means that the alloy will crush sooner and more easily on the front than the back and will allow the base of the bullet to deform essentially none due to gas pressure, i.e. NO RIVETING while the front and middle squeeze down several thousandths and in some cases elongates the bullet from the back to the front. Also, remember this is a bullet made of 10.5 BHN putty which has been artificially reinforced by quenching and precipitation hardening to nearly double the test number in "hardness", and the front goes from 29,000 PSI strong to more like 15,000 PSI strong as soon as the shoulder and front bands begin to deform into the throat. Yet, we don't crush the back end so the alloy is STILL 29,000 PSI strong. All this lets the bullet engrave easily without distorting the back, and doing that gets the bullet straight into the bore without bending, riveting, or collapsing at its grooves. The only hurdle remaining is keeping obturation up with weakened driving surfaces at 2,400 fps and 180,000 RPM a couple inches from the end of the muzzle. Remember, crushed alloy gets instantly hot, add barrel friction and a barrel that's hot to begin with, and the fact that lead alloy loses strength at a rate that's the square of temperature, so the bullet might really be something like 8 bhn at the drive side of the bands, at the muzzle. This still works though because if you calculate through F.W. Mann's exhaustive formula the pressure on the engraving/torsional bearing area of a bullet like the MP-30-180 Silhouette for a .004" land height and four grooves, the pressure is only about 10,000 PSI (a lot less than that many pounds on a lot less than a square inch, actually, but the same "per"), and the bullet metal at BHN 8 will take over 11,000 PSI of force to deform it. If your lube and alloy blend keeps the abrasion down, you can JUST pull off the launch without losing obturation and getting the accuracy-destroying drive side wear, loss of obturation (leaks), lube blowout, leading, and a damaged bullet which won't fly straight.
Now, try the same thing with 22 BHN Linotype alloy and see what you get. Spoiler alert, it's not even minute of berm accurate and will teach you right quick that there's more use for a Chore Boy pad than cleaning stuck grease out of pots and pans.
Further, try NOT water-quenching that alloy and instead add a .001"-thick, 30 BHN, self-lubricating, heat insulating jacket. Instant good results. Why? The slicker than lead coating reduces engraving force even more than a stiff but crushable alloy alone, so the 15,000 PSI strength of the air-cooled, 10.5 BHN base is enough to hold the base in form until the gas check goes in the throat and also adds surface strength and heat insulation to keep the alloy strong while it shoulders the rifling twist and hauls ass out of the muzzle without leaking or getting washed out.
I forgot where I was going with all that, but maybe if anyone actually read all that it will at least make what some of what Fiver wrote make more sense.
fiver
Well-Known Member
well to touch on the lube thing a little.
the lube has to do a couple of things.
1 make it to the barrel without being blown there by the initial pop.
2 seal the gas in the corners.
3 it has to make it past the relax point down the barrel without getting hard again and leaving a bunch of gunk behind.
4 the muzzle...
you got no idea how many times i've winced when i read all about the big wet star at the muzzle.
now the issue here is wet is fine since it's spinning all [? maybe?] the lube out of the grooves.
or maybe it ain't or it's coming off unevenly.
it's also probably leaving a nice wet coat of lube behind.
or you got the other problem and the lube ain't really lubing much and gets flung off in chunks where the lands cut it.
the idea is for it to seal and be able to flow under pressure.
it all stays or it all goes.
it also has to take in that little bit of lead being pushed back by the rifling, the wall angle keeps it [the lead] locked in place, or allows the land to simply and easily pass through without causing the little trailing edge,,,, so that ain't being ejected at the muzzle too.
things get real complicated when your factoring in alloy flow, engraving, displacement, and what the lube is supposed to be doing all at the same time.
tuning a lube seems like a fallacy to many and they try to break it down to temperature windows or cut off lines or whatever and most everything seems to work okay in one fashion or other.
the reason is because so little is actually needed and most of it does nothing but hang out and look good.
i don't really want to go into friction variables and such so if you ain't got no leading, a big wet goober at the muzzle, chunks on the paper, or smears of lube 10"s from the muzzle,,,,, what your using is doing just fine.
the lube has to do a couple of things.
1 make it to the barrel without being blown there by the initial pop.
2 seal the gas in the corners.
3 it has to make it past the relax point down the barrel without getting hard again and leaving a bunch of gunk behind.
4 the muzzle...
you got no idea how many times i've winced when i read all about the big wet star at the muzzle.
now the issue here is wet is fine since it's spinning all [? maybe?] the lube out of the grooves.
or maybe it ain't or it's coming off unevenly.
it's also probably leaving a nice wet coat of lube behind.
or you got the other problem and the lube ain't really lubing much and gets flung off in chunks where the lands cut it.
the idea is for it to seal and be able to flow under pressure.
it all stays or it all goes.
it also has to take in that little bit of lead being pushed back by the rifling, the wall angle keeps it [the lead] locked in place, or allows the land to simply and easily pass through without causing the little trailing edge,,,, so that ain't being ejected at the muzzle too.
things get real complicated when your factoring in alloy flow, engraving, displacement, and what the lube is supposed to be doing all at the same time.
tuning a lube seems like a fallacy to many and they try to break it down to temperature windows or cut off lines or whatever and most everything seems to work okay in one fashion or other.
the reason is because so little is actually needed and most of it does nothing but hang out and look good.
i don't really want to go into friction variables and such so if you ain't got no leading, a big wet goober at the muzzle, chunks on the paper, or smears of lube 10"s from the muzzle,,,,, what your using is doing just fine.
462
California's Central Coast Amid The Insanity
Yep, the boy's good, ain't he?
Fiver's last is the longest I can recall him ever posting.
I'm going to copy them for Winter reading.
Don't stop guys, keep it coming.