Effect of Powder Coating on bullet velocity

Snakeoil

Well-Known Member
"A 34.6 grain load in 30/06 with the FA 173 grain boat tail was listed at 51,000 CUP in the early 1950's. Our target load in '03's is 16 grains with the 200 grain cast bullet. I have seen two double charges of 32 grains. Luckily both were Remington WW2 actions that bulged the barrel shank's square threads into the receiver requiring machining to remove the barrel. Both case heads failed releasing gas into the action and both blew the magazine floor plates out and cracked the stocks. Both shooters had powder burns and splinters in their right hands. Cone breeched actions are not the ones to be shooting when this happens.

Reduced case volume and a cast bullet in the 308 must be making enough for the primer to blow
."

I forgot to mention that the floor plate, follower and spring were blown out onto the bench. Inspection by a member who is a gunsmith and has owned a shop for many years said no apparent damage to the rifle.

I truly appreciate the very detailed responses. I'm a little better informed today. I hope it sticks. Gray hair is working against me. But I do find that if it is a subject I truly enjoy, it tends to stick. When the info is analytical in nature, I don't think you need to remember it, it just folds in with the info already stored in the gray matter.

I've loaded 30 rounds with those PC bullets. I weighed them and they are a nominal 167gr.. They are bevel based, so that might work against them for accuracy. Although the BB bullets I got recently with a .38-55 Browning Traditional Hunter have shot well in their first trip to the range. Will be taking that rifle with me as well. It now has a set of Steve Earle's blocks and my 10X Lyman STS will be on it. Excuse list just got a bit shorter.
 

Snakeoil

Well-Known Member
Back from the range. Brought my ProChrono DLX and shot the PC bullets at 100 yds just to see how they worked in my 03. Also brought my standard load of SAECO 315, 170gr truncated cone GC over 18gr of 2400 as a baseline comparison.

Wind was blowing a bit and later in the day we had a little snow squall and a small white tornado at the 500 yd line. But that is just filler info.

Shot the 03 off the bench at 100 yds. Scope was my Lyman STS. Use my normal sight setting for my standard load. The PC bullets weigh nearly the same at about 167 gr and same charge of 2400. Primer was CCI match in both.

First few rounds were high and I brought it down. Then it was left and I brought it right. Then it was right and I brough it left. Then it was low, then it was high. I hit the swinger, a 12 inch plate once or twice and then had bullet movements as much as 4 feet between shots. So, I switched to my standard round and once dialed in, drilled pretty much one hole on the plate. Back to the PC bullet load and it was like throwing rocks at the target. I gave up and decided to pull the rest of the bullets rather than just burn powder for nothing. I put about 15 rounds downrange at 100 yds to produce about a 4 foot overall group. There were times I would crank 10 minutes of windage into the scope and put the next round in the same hole. Then I'd send another downrange and it would move 3 feet to the right. You'd have to be in a hurricane to have wind move a bullet that much at 100 yds.

Average velocity was 1603 fps with SD at 44 fps. Extreme spread was 166 fps. So, the powder/load was working pretty good. Maybe this bullet needs to go faster in order to stabilize. I'm at a loss. Now I know why my shooting partner struggled to get on the target when he was shooting that bullet.
 

Ian

Notorious member
Those chronograph numbers are dismal.

Did you read through my lengthy post about PC earlier in the thread? Have you been following Fiver's "hypothetical question" thread? I get single digit SD for ten rounds of PC once I get the load dialed in. If it were me, I'd be really tempted to try those again with a starting jacket load of 4064 or 3031, assuming they are at least 13 bhn and are gas checked.
 

Snakeoil

Well-Known Member
I was under the impression that any SD below 50 for smokeless was pretty good. I'm certainly not an advanced rifle shooter. The only serious rifle shooting I've done, other than .22 was BPCR with a .45-70. So, this is my first foray into smokeless rifle reloading and I'm leveraging the experience of some of the other more experienced guys at the club.

Bullets are not gas checked. They are bevel based. Yes, I know that BB are not ideal. But today I also shot my .38-55 Browning TH out to 500 yds with 17gr of 2400 behind a 249 gr BB bullet and shot MOA to 1.5 MOA at 500 yds. The SD for those was 37 fps. Bullets were lead from lasercast with whatever lube they use. I got about 2000 bullets with the rifle. So, I'm very pleased that they shoot well.

I never tested the hardness of my bullets. Probably should. My BPCR bullet was a Paul Jones 530 gr Postell poured from 25:1 lead/tin mix. They worked and I'm not one to try and fix something that works.

And yes, I read your response and everyone else's. Also saw that thread by Fiver. One of the things I struggle with here are all the abbreviations. Somebody should post a glossary in the intro section with all the abbreviations and their meanings. I pondered what RD was for most of last night and still cannot come up with what that is.

I have to say that the regulars here seem to speak in some sort of code language. I guess it is shorthand, but for new folks, it's almost like it's a secret language. I've seen this with other forums so I guess it is human nature. I figured out that RC is a Rock Chucker. PC drove me nuts so I did a search and still was not sure what was meant by Powder Coated bullets. I thought for sure it was some magical substance known only to cast bullet shooters. I'm very familiar with Powder Coating, but never thought it would be used on a bullet. So PC belongs in that glossary, too.
 

KeithB

Resident Half Fast Machinist
Most of the referral to RD I think is for Ranch Dog. The guy that developed these under that name did so mostly for lever guns as I understand it.
 
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Brad

Benevolent Overlord and site owner
Staff member
Yep, an RD bullet was designed by Michael of Ranch Dog Outdoors.

So the real question is this- If I fire my Marlin CB, off my BR, with a PC’d GC RD bullet loaded over RD what will be the SD? What if it is cast from WDWW?
 

KeithB

Resident Half Fast Machinist
What's scary is I understood that sentence the first time I read it.

According to the Hitchiker's Guide the answer is...
 

Ian

Notorious member
Shorthand, yes, we kind of get in a hurry sometimes.
Ok, bevel based. I'm back to pressure curve and maybe not enough jump. If the base band gets gnaw marks through the PC from from being gas cut, the bullets can sometimes hit sideways at 25 yards with foot patterns. Off thebtop of my head I'd say size the bullet down to a half thousandth smaller than throat entrance diameter, give them no more than 1.5 thousandths neck tension, and give them about 20 thousandths head start (jump) to the throat. Leave some flare on the case mouth to center the neck.
 

RBHarter

West Central AR
Snake oil never hurts to ask when in doubt about terms . It took me almost a year to figure out what mule snot is turns out it is Lee alox bullet lube ..... Felt dumb . There's always going to be a new short cut , especially on a small forum where it's very often the same group of 20-30 or less . We get used to the shorts and sometimes the new guys spend a lot of time trying to figure out what was said .
 

fiver

Well-Known Member
166 ES will show up on paper at 100yds as 2"s of vertical each direction from POA.
that's no correction it's deviation.
I done a big write up on it over at CB a few years back showing it get worse with 3 different barrel lengths because of the higher velocities with the longer barrels.
I needed to use a filler with that load and as soon as I added it, and more powder the large swings went away.
and the groups tightened right up.
[different powder and case size, but still the same-same as here]

one little thing nobody thinks about with 2400 is it is position sensitive in the 0-6 at the 17-19gr. volume.
 
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Ian

Notorious member
True, but his normal cast loads would still group where the PC bullets would not. The principle and most obvious difference being the gas check on his normal bullets and less so, the coating.
 

fiver

Well-Known Member
if they are the bullets I'm thinking they are I wouldn't use more than 12-13grs of unique with them no matter what they were coated with.
happiest day of my life when I sold that Magma commercial mold, even if it did shoot good in the 7.5 swiss rifle at 50yds on top of a lee scoop of unique.
30/30 165GR. RNFP
 

Snakeoil

Well-Known Member
Believe it or not, I understood most of that sentence, too. Not sure was WD Wheel Weighs are, but I'm sure I'll find out. My Dad and I used to by RD by the 12 lb keg when we were both seriously shooting trap. This was back in the 60's.

I'm reluctant to use a filler in a bottleneck case. I've used Dacron batting in my .45-70 with smokeless loads. But the batting becoming a plug at the neck scares me a bit. I've read reports of ringed chambers from fillers. I've also read reports of great success will fillers. Even the Lyman book mentions Dacron batting fillers which is why I was willing to try in my Shiloh.

The GC did not occur to me. Part is pure ignorance on my part and part is the BB lead bullets shooting so well in my Browning with a very similar powder charge. But ignorance abounds here on my part and never considered the effect of gas cutting on the PC making the bullet leave the bore in a less than ideal condition.

Position sensitivity is something I've considered. The guys at the club that steered me to 2400 said that one of the reasons is that is supposedly not position sensitive, or not AS sensitive as other powders for reduced loads. I do tap the bullet on the bench before loading it into the rifle and close the action slowly. The rifle is in a rest so slightly angled upward. But it is not a steep angle because the club has a rule about this since there are houses downrange of the 500 yd berm. We've had some rounds go over the berm due to AD's caused by extremely light triggers. One RB fired when the action was closed. That particular individual is no longer a member. As a side note, he did the same thing in his basement. Chambered a loaded round to make sure it fit and when he closed the action, BANG. It hit his bench grinder on the other side of the basement and pretty much destroyed it. It was a .45-70 BP round. That Sunday at the club, there was a new target hanging at the 500 yd line. When you looked thru the spotting scope, the target was a bench grinder cut out of plate steel. He packed up his gun and never came back.

Tangent. Sorry. So Fiver, are you saying 2400 is position sensitive in a large case like a .30-06? Like so many things these days, an attribute assigned based on limited criteria gets the criteria left off when it is repeated by others. I'm wondering if this is where the belief came in that 2400 is not position sensitive.

We do get unexplained fliers with the SAECO 315 and 18 or 17.5 of 2400. We normally attribute it to some of the crazy wind and mirage conditions we get at Wilton. I have wondered if it was position sensitivity playing at least a partial role and hence my practice of tapping the round before I chamber it.

I honestly did not try to construct a perfect round with the PC bullets. I left my die set to seat the bullet like it would seat the 315 bullet. I do not bell my chamber mouths, but rather use an M-die. I make my own M-die plugs based upon the bullet and the case size. I'm using about 0.002" neck tension on a bullet sized to 0.312-0.315. It is a range because the 315 comes as-cast at 0.312 but I use a 0.313 sizing die so the check gets sized and maybe the 1st two base bands of the bullet. The upper bands are smaller out of the mold. The PC bullet measures 0.311, so only about 0.001 neck tension. How much jump was present I cannot say. But it certainly was not engraving the lands when chambered. Maybe the combination of the gas check, the bigger bullet and more neck tension contributes to the 315's accuracy. The smaller diameter of the PC bullet might also be a detractor, although prior to slugging the bbl on my 03, I shot 0.311 bullets thru the rifle with good results.

Referring back to Fiver's Hypothetical thread, the detailed explanation of pressure changes due to bullet movement, stopping and then moving again, aka jump was interesting. What was news to me was this issue of some powders needing pressure in order to ignite and reduction in said pressure could cause the power to stop burning until the pressure built back up again. I have to assume that the need for pressure is based upon the specific application for which the powder was intended and when a different application is used, it needs to be considered. My question is, how exactly does one determine these characteristics. There is no mention of it that I recall (gray hair in play) in the load manuals I have. I certainly don't remember every seeing it in the OEM loading pamphlets for their powders. Are some of the members here running pressure tests with piezo devices to determine this stuff. Of is it published somewhere and I simply have not found/seen it yet?
 

Ian

Notorious member
Ah, we're getting into the important stuff now. The '06 throat entrance should be .311" or a titch larger, but it IS a funnel and with the bevel-based PC bullet you can go a lot smaller and not lose much throat support. I'd size them .309" and reduce the prepared neck size accordingly. The focus with plain-based PC is REDUCE THE ENGRAVING PRESSURE in every way possible so the base and base band doesn't get chowdered to buggary by the powder gas working against a heavy engraving load. Imagine pushing a car up a steep incline and buckling in the trunk lid by hand pressure vs. pushing it on flat ground.

Another tip, if you're sizing the necks in a FL die and not uniforming the neck diameter by "turning", you are over working the brass and I guarantee the bullet is not being held statically in the center of the bore when the cartridge is chambered. This matters a lot with any bullet, but especially PC because the coating can get raked off the surface if the bullet is forced into a crooked start. Neck bushing dies or FL sizing dies with selectable bushings minimize overworking the brass and tend to keep the fireformed necks more on center due to less drawing of the brass. Necks will always draw from the thinnest/weakest part and that makes them stretch off center. Mimimize the stretch, minimize the eccentricity. Always bushing size slightly smaller than you need and uniform the necks back out with an appropriately sized expanding spud. OE dies typically make the neck ID about .303-.304" with the expanding mandrel taken out and that's a LOT more than you need. It's a lot worse if your brass has necks on the thicker side.

Stop-start is not the same as jump. Jump is creating distance to the lands by seating the bullet deeply enough that no part of it, or very little, touches any part of the leade and it can move forward some (a little) before contacting metal. Doing this gives the bullet some inertia when it hits the throat and begins to swage through, which reduces pressure spikes that can mutilate the bullet base or base band.

What happens with the start-stop-start thing is the primer pressure pushes the bullet forward a little until it runs out of poop. If the powder doesn't pick up and continue the ignition pressure right after the primer lights because loading density is too low and/or it was simply too heavily-deterred to ignite within the system you created, then there is a smolder/hangfire. During that smolder, the deterrent coating burns away and your half a case (or whatever) of 4831 or H-110 suddenly becomes half a case, plus the increased volume due to the bullet being displaced by the primer, and with the deterrent compromised or mostly gone, lights off like Bullseye or even straight nitrocellulose, i.e. KABOOM. We're talking microseconds here, but if that bullet stops in the throat it becomes a bore obstruction with dynamite behind it, i.e. Secondary Explosive Effect or a pipe bomb.

PC is slippery as heck, with only a thousandth neck tension and some jump, your 2400 load is WAAAAYYYYYY out of whack. Switch to a faster powder.

Dacron is perfectly safe if used CORRECTLY, which for some reason is hardly understood. It is perfectly save in bottleneck cases IF installed correctly and in the appropriate situations.

2400 is terribly position sensitive in large cases at low load density. This is due to the spherical shape and heavy deterrents making it relatively difficult to ignite compared to, say, Herco or Unique. Unique is also quite position-sensitive in the '06 case, but not as bad as 2400. This ends up making wild SDs due to slight fluctuations in how the powder is blasted around inside the case by the primer. I doubt you prep your flash holes and the burrs there are different on every case, exacerbating the ignition consistency issue if it is dicey to begin with.

Titegroup is the most position-insensitive powder I have ever found. 6.4 grains of it in a .308 case with slippery powder-coated bullets yields single-digit SD numbers every time.
 

Brad

Benevolent Overlord and site owner
Staff member
2400 is position sensitive. The farther you shoot the more it shows up. The wide variation in velocities is a sign.
The need for pressure to burn is why some powders, like H110, don’t do well with reduced loads. The powder needs pressure to keep good ignition. I don’t have “proof” but will venture a guess that deterrent coatings are the core issue.
I don’t own a 315 mould and have never really looked at one but isn’t it a tapered bullet? That would make pressure build up slower as the bullet moves a fair amount before fully engaging the rifling.
I would try slowly increasing powder charge with 2400.
 

fiver

Well-Known Member
don't take this wrong but powder burn characteristics are in the load manuals.
you have to dig and you have to compare and you have to make some serious mental notes, but they are there.
the old IMR books show powders all up and down the scale in places you wouldn't even think to use them on your own.
Lyman shows them too, but..
have you ever wondered why they don't show pressures next to most of their loads?

you have to look at many of the powders available to us in other applications to see the trends they portray.
you won't find it for all of them but probably a small sample here and there that you can add up and carry over to other powders with similar base stocks and additions.

powders that do weird things in stressful situations just sort of disappear from the shelves real quiet like.
sometimes they are slightly re-formulated and return as something else, sometimes they don't.
but those types of things also add up to telling us how certain formulations will behave under higher or lower pressures.

for example a powder known for spiking pressures into the stratosphere when placed in a confined area is exactly the powder you want in a wide open low pressure low speed situation.
you know a very small amount of it will ignite easily, all of it will burn, and it isn't really gonna matter where it is in that space if the sparks can get to it.
powders that are the opposite are ones that are great for cramming into a much smaller case size and burning everything off with just enough pressure and gas to accelerate the bullet to XX feet per second.
too far,,, you don't get quite enough pressure to burn well and you lose the efficiency. [there's ways around this but we ain't here for that]
 

Snakeoil

Well-Known Member
I'm starting to drink thru the firehose here. But keep it coming.

Couple of things. First, I debur and chamfer all my primer holes and always have since starting BPCR competition 20 years ago. I actually make tools to do this so it becomes a pretty simple task.

The point Ian makes about sizing down to .309 is counter to everything I've ever learned about shooting cast bullets. Normally, I'd look for groove diameter or maybe 0.001 larger. Hence my 0.313 sizing die for the 315 bullet.

I'm surprised that folks are not familiar with the SAECO 315 bullet. I shoot with a few Schuetzen shooters and that bullet design in any caliber is considered a good choice. Here is a picture of one from the Meister Bullet site.

SAECO 315.jpg

The noise is a true cone. The back band and I believe the next one up are about 0.312 out of the mold. The next three and the nose are 0.310. I'd have to go measure a bullet for that 0.310 dimension to be sure.

When I started working up a load, I leveraged the experience of the guys already shooting it. They were quite happy with 17.5gr of 2400. My testing at 100 yds gave me better accuracy with 18 gr so that is what I stuck with. My approach to bullet depth, which comes from my BPCR experience, is using an empty case with good neck tension, I barely seat a bullet and then chamber it and push it home with the bolt or breech block. I then carefully tap it out with a rod, examine how deeply it engraved the lands and then adjust. My goal is to just engrave the lands. However, with this bullet and the .30-06 case, not much bullet was in the case. I was getting an occasionaly flyer which I mentioned before. A friend who was shooting a better score was seating them deeper so I thought I'd give that a try. The problem is range conditions of wind and mirage add variables that make it hard to determine if flyers are me, the load or the conditions. Everything is normally shot with my 10X Lyman STS. Although iron sights are required for some matches.

So, getting back to PC, the comment that my 2400 load is way off is the most striking so far. I was under the impression from both powder burn rate charts and the fact that 2400 is sold as a pistol powder that it burns pretty fast. But from this comment, I get the feeling that it needs some pressure in order to properly ignite. I do have an old lb of Unique. A number of guys at the club are using that in ultra-low velocity loads. Some of them sound more like the rifle is a Crossman. But, I could try a load with Unique with that same bullet just to see if it would tighten up the group. And I have to be honest here, I'm not looking to move to PC bullets unless it is to my advantage. This whole exercise started because my shooting partner could not get them to group worth a damn and neither could I. Curiosity is a terrible affliction. The desire to learn new things every day is right behind it. So, here I am.

Last point, I neck size the 06 cases using a Lee collet die. I like the premise that it uses a mandrel to determine the sizing, which also centers the neck and that is limited only by any case thickness variation in the neck. I thought about turning the necks, but am not to that point yet. I've measured them and they are pretty good if I remember right. They are all new Federal cases. Well, they were new. About 1000 rounds thru 60 cases now with one neck annealing event in the middle.

I'm going to go read thru my loading manuals to try an become a little better informed. This deterrent thing is something new to me. I realize that the chemists that create the powder need ways to establish the burn rate. But being a KISS kinda guy, I assumed it was just that burn rate. In other words, pour some on the ground and one will burn faster or slower depending on the chemistry. But now I know that it is a lot more than that and what happens inside the case is another variable that affects burn rate. Damn... why can't this stuff be simple??!!!

One more last point. Someone, I think I might have been Ian, said that 2400 was a ball powder. Unless I've been misinformed for many years, I would call it more of a stick powder or extruded powder. It looks like mechanical pencil lead cut into tiny pieces. Ball powder to me is round or pellet shaped.

And one more last point. Gee, I never seem to run out of these. I just bought 8 lbs of 2400 because I went thru my 4 lb jug in short order. I really want to get this stuff to shoot well for me with my 315 bullet. But, if I am grasping at straws here, tell me now. I'm sure I can peddle it to the other guys that shoot it.

Thanks again. I'm enjoying this and learning a lot.
 

JWFilips

Well-Known Member
In my 30-30 340 Savage: The 165 gr Ranch Dog from NOE with traditional lube grooves is a winner with Traditional lube and now with PC! But that SAECO 315 is also an outstanding bullet! Of couse I'm shooting these with light loads but they are some of the most accurate in the 1100-1200 fps range