Ways to consistently increase pressure for gallery loads

BHuij

Active Member
Thanks all for replies. I believe I haven't been very clear what I'm trying to accomplish here. My primary purpose for starting the thread was just to learn. While I totally appreciate that it's difficult to build a load for a rifle to meet certain goals without doing lots and lots of testing, I find that understanding the theory behind what happens as a result of changing various parameters is really useful for me to make educated decisions on what to test next. In other words, I like to know the "why" and not just the "what."

I think one of the reasons things haven't been clear is that I'm asking some specific questions that relate to various ongoing projects of mine, so it looks like I'm just wandering around aimlessly here :D Let me try to be a bit more specific.

Project #1 right now is finding a reasonably accurate cast .223 load for my AR-15 (aiming for 2 MOA), one which cycles with 100% reliability. The rifle is as basic as they come: 16" barrel, 1:9 twist, carbine-length gas system without adjustable gas block, standard buffer spring and weight. Basically made to sling cheap 55gr surplus ammo. The mold I have is the Lee 55gr FP (.225"). It's not that great of a mold and my static fit is pretty bad. I realize that the very best thing I could do to improve accuracy is to buy a better mold, but that's not in the cards right now, so I'm trying to use this as a learning opportunity, and see what I can achieve by experimenting with other changes that I CAN make right now. Specifically, bullet hardness as measured with BHN, powder type, and powder charge.

I have done lots and lots of testing. Without going into too much detail, I have been juggling various combinations of the three factors listed above. Namely, bullets ranging from BHN 12 to BHN 35, different powders (specifically IMR 4895 and H335), and loads everywhere from "so low it barely cycles" to "hot jacketed loads." So far, my best and most accurate results have inarguably come from the BHN 35 bullets. There has been no load in my testing using BHN 12, 18, or 26 bullets that was more accurate than the same load with BHN 35 bullets. To me, this makes sense. Yes, my bullet fit is working against me, and perhaps nothing else I can do will fully overcome that problem. But it seems like the higher the BHN, the more resistant the bullet will be to deformation under pressure. I have heard numerous people say that after a certain point, increasing BHN actually leads to worse accuracy, but nobody has actually explained why yet. So not only has this not matched my experience, it also seems to contradict my best attempts to understand WHY extremely high BHN bullets have performed best for me.

Interestingly, my best results have been with these 35 BHN bullets and also my highest velocity loads tested to date, using IMR 4895. I got about 4 MOA with a 10-shot group of these hard bullets over 20.5 grains of IMR 4895, which came out just over 2700 FPS. Oh, and no loads of mine have ever leaded my AR bore, no matter how hard or soft the alloy. I would think you'd need to mess up pretty badly to get leading with powder coated, gas checked bullets.

So I have just finished loading up what will probably be my final and definitive set of tests to see what my 35 BHN bullets are capable of. I have loads ranging from 18 grains of H335 to 25 grains (approaching book max for 55gr bullets), and from 18 grains of IMR 4895 to 24 grains. If none of these loads get me to 2 MOA as I'm hoping, I'm having a hard time believing that a high BHN is contributing to any inaccuracy, or that lowering the BHN might tighten up my groups. Perhaps I'm wrong, and if so I hope someone will explain to my why that is. If all of these loads fail, then the only thing I can think to try is a slower powder than 4895 (maybe RL 12 or 4064?), or playing with different additions to my alloy. I have a small amount of high-antimony lead which is a blend of linotype, electrotype, and monotype which I can mix in with my COWW, and I think that would probably help.

So bottom line is, I know the "right answer" is to get a better mold, but since that is not doable right now I'm trying to learn what else I can tweak to improve my results within the limitations presented by the poor fit of this mold. For the purposes of this load I actually don't care about velocity at all. It could be a 1000 FPS load or 3000 FPS, and as long as it hit 2 MOA and cycled 100% I'd be happy. Just so happens that my best results have been at quite high velocities with very hard bullets. Within my working hypothesis for what was mainly causing my inaccuracy (deformation upon firing), it kinda seems like the higher the BHN the better in my specific scenario, and my results bear that out thus far.

So as far as theoretical questions I have posed here, I think it boils down to:

1. What causes higher BHNs to be detrimental to accuracy? Is it failure to obturate? Something else? And why have my results been best with 35 BHN bullets if 35 is apparently way higher than I should be using?
2. If I wanted to use a lighter load (~2100 FPS) in an attempt to keep chamber pressure down and thus reduce bullet deformation, would increasing neck tension help me get a better burn? The answer here seems to be "probably, but at the expense of causing different and likely worse problems."
3. Is there some way to get a good consistent burn in a reduced load with either stick powder (4895) or ball powder (335)? The answer here seems to be that consistent burn simply requires higher pressure. It doesn't matter which method is used to get higher pressure (increased charge, magnum primer, filler, heavier bullet, what have you), it's the higher pressure itself that is going to deform the bullet anyway. Meaning that the best I can hope for with a reduced load is that maybe it's low enough pressure to allow my bullet to stay straight from chamber to muzzle, but the burn and therefore velocity will be inconsistent and I'll always have vertical stringing.

The verdict appears to be that "reduced loads" and "consistent burn" are diametrically opposed concepts. I'm beginning to lose hope that there might be a "sweet spot" window where pressure is high enough for a good consistent burn, but low enough not to screw me over when my static fit is as bad as it is. If this "sweet spot" exists at all, it seems to me that the harder bullet I can get, the higher pressures I can get away with before the bullet accuracy is destroyed. And if it exists with H335 or IMR 4895 and my current alloy, I suspect my next set of tests will find it. If not... maybe a different alloy, maybe a different powder. Maybe both. Maybe there really is no way to get 2 MOA at with any cycling load using this bullet in my rifle. I'd like to believe there is... but maybe not.
 
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Bret4207

At the casting bench in the sky. RIP Bret.
Okay, you're doing a lot of things all at once. First off, BHn IS NOT an indicator of potentially better or worse cast accuracy. IOW, no one is saying that a 35BHn bullet will always give worse accuracy than a softer one. What is being said is that sometimes a harder bullet will give worse accuracy, but it's not an absolute. It's just that it's easier to use a softer bullet if it will work than trying to make one harder without trying the softer stuff first because we assume harder is better. That's the whole ""hardcast" thing again. So, you aren't using a harder bullet than you should, you just didn't make it clear that where you were already at and that it seemed to be working.

That takes us to part 2, You are already getting your best groups at high pressure. I don't believe that even 35BHn bullets going to be deformation free at pressures like that. It's entirely possible you are deforming the bullet, even though it's relatively hard, and it's slugging up to fit the barrel better already. You have to remember we're dealing with a game that works in thousandths and ten thousandths of an inch making a big difference. That same load with a bullet with a 15BHn may be blowing it to pieces (erroding it, gas cutting) while the harder one is hanging together. As to the "why" of why a harder bullet sometimes has poorer accuracy or leads where a softer one won't, that's all theory. The common theory in the dedicated cast world is that the softer bullet is going to obturate to a point that gives better fit and that the harder bullet doesn't obturate quite as much and give you problems. Logic says that if that were the case, then kicking the harder bullet with more powder would overcome that and seal the bore like the softer one, but it doesn't work as simply as that. There doesn't appear to be a linear progression to it. At some point you have to admit that we just don't know what we don't know! We can't see what actually happens, all we can do is guess at "why" based on our observations. So while you are thinking that the harder bullet is resisting deformation better and giving you better groups, I think the harder bullets are at a better balance point with the the high pressure load you're using and are slugging up just enough to give you better dynamic fit. We see the same basic thing with much softer alloys using much faster powders.

Part3- You're powder coating. I know absolutely nothing about powder coating and really have no interest in it for bullets at this point. But, I imagine it contributes to the OD of the bullet. The mould is designed to drop a nominal .225 bullet. What are your's after PCing? What is the ID of a case mouth fired in that rifle with a full bore load? What is the diameter of a bullet after you seat it? You might want to pull one and see if it's getting swaged down in seating. And if you're powder coating, from the tiny bit I've read on it, isn't that a coating that keeps leading down anyway? Would that explain why you haven't had any leading issues? And trust me, you most certainly can get leading with just a gas check! I think the PC is a big factor, probably why so many are into it.

Part 4- You aren't going for a gallery load at all. Not at 2700fps. Are you willing to try different powders? Powder isn't cheap these days, it's not a $10 risk to buy a faster powder any more. But the $25 mould might never get you where you want. It's your wallet. Which kind of leads to Part 5- If the bullet have static fit so poor that you know it's bad already, there comes a point where it just isn't going to get any better no matter what you do. A heavier, better fitting bullet will help with your better burn desire without using unusual neck tension and might give markedly better results at barely cycling the action pressure/velocity. Some bullets just aren't right for a particular gun. You are going to have to decide which direction you want to go. You're already into this in a platform that isn't real cast friendly to start and you're getting 4 MOA at 2700fps. That ain't bad at all for a poorly fitting bullet!!! Theres also the chance that you're doing as good as that particular rifle will ever do.

You are looking at a lot of things all at once and you're going to have to break them down into specific pieces and work on one thing at a time.
 
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Spindrift

Well-Known Member
Very interesting thread!
Bhuij: have you established the accuracy potential of the rifle, with jacketed bullets?

I am no expert, but would suggest working with a faster powder (like 2400) first. It would probably not cycle your gun. But you would probably get an impression what accuracy level is achievable before moving to the slower powders. Good luck!
 

RBHarter

West Central AR
PC changes everything .........
I would suggest 10x or H322 maybe H4198 . 10x and H322 worked well in my bargain basement AR . 4198 was more accurate and has a dramatically flatter curve than the others .

I work every load as if it were to be a hunting load for the biggest critter I would deliberately hunt with it . That makes my goals different than many others .
I also don't PC at this point .
 

fiver

Well-Known Member
try this.
1 parts lino type, 3 part ww alloy, add in another 1% tin.
check and size 225-226.
put it on top of 20grs of 4895 and work up in 1/2gr increments.
 

Ian

Notorious member
.22s don't play by the same rules as 30s exactly. You need a little more of that internal bracing to take the throat transition without damage.....and that alloyed toughness is completely different from heat-treated toughness. The difference with the .22s isn't raw pressure, it's the speed at which the light, small bullets pop out of the case and smack through the throat compared to larger calibers. Your alloy has to be up to the task, or the static fit has to be perfect, and you're not going to get perfect static fit with a semi and have function. There needs to be a little wiggle room, and the alloy has to be tough and flexible enough to roll with the punches that a little bit of jump and dynamic misalignment dish out.

Don't read that as you need HARD bullets, understand that it means you need a better-braced bullet that's still flexible (to stick with Fiver's house moving analogy from earlier in the thread).

Also, a caveat about trying to paint things with a broad brush. There are some general truths, but they involve the physical behavior of alloys under pressure, and the effects of fit and loading technique and cannot be boxed into categories like "hard bullets shoot more accurately" or "minimal deformation shoots best". I've shot 10.4 bhn AC 50/50 bullets at jacketed speeds to very good effect in several rifles, and some of the best-shooting loads I've ever put together had the bullet completely change shape during firing.....and also had the opposite be true when other factors in the system were different.
 

Bret4207

At the casting bench in the sky. RIP Bret.
"Internal bracing", I like that. Good way to picture it. Trying to get the "hard doesn't equal strong" idea across is difficult. I don't know how to put my ideas on soft/hard/strong/tough/resilient into an easy to read proposition. It's confusing even after it's been explained by people far better at it than I'll ever be.
 
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Ian

Notorious member
Something I forgot to mention about the .223/5.56 and "normal" speed powders. Pretty much everything from 4198 to 4064, including H322, H335, Ball C2, Varget, 3031, 4895, etc. etc. all peaks pressure between 1.5 and 1.9" of bullet travel. You may be looking at 42K psi at 1.6" of travel, and a steep curve (everything except H335 and 3031 have a steep curve), but during the first 1/8" of travel the pressure may only be 2K......or 20K psi. The pressure isn't the big problem with bullet deformation, it's the speed that it hits the throat....even at 1/8" of travel.

Yes, Bret, it's an abstract concept. Best way I can explain it is comparing water-quenched WW alloy to Linotype. Same BHN, at 22-24. TOTALLY different behavior in a rifle barrel, or when placed on an anvil and clobbered with a hammer.
 

BHuij

Active Member
This makes sense. Thanks all. Ian, thanks for that info about peak pressure as well, that's really good info. As far as sizing, I've been using a Lee push-through .225" sizer to size once right after casting, then to seat the gas check, and finally to size one more time after PCing. Micrometer confirms .225" actual bullet diameter. I think bumping it up another thousandth or so might give me a little bit better fit, so with this batch I did not size after PC. Mics out to .226" actual diameter now. We'll see if that helps.

If you're saying HT'd COWW is too ductile to survive the jump through the throat without going crooked in the bore, and adding antimony will help remedy that, then by all means my next set of tests (assuming I can't get what I want with these tests) will be using a higher antimony alloy.

Oh and @Spindrift I do have 4 loads of Hornady 55gr FMJ's loaded up over H335 as a sanity check as part of my next set of tests. If the jacketed bullets will group, then I know this whole thing hasn't been a wild goose chase with a bad rifle :D

Since I will at some point want to get a nicer mold, is there a specific NOE mold you guys who shoot HV .223 would recommend? There are a couple slightly heavier ones in the 60-70gr range on their site that look quite good.
 

Ian

Notorious member
It isn't just antimony you need for this, it's the tin too. The bracing and resistance to shear comes from the combo of Sb/Sn in the lead mix. The reason for 6/4 is with guestimation of components it insures you won't have more tin than antimony, but you have enough of each and not too much of either one.
 

fiver

Well-Known Member
one more.
diameter that ain't your fight.
you'll press the bullet to size no problems.
the trick is keeping it from getting bigger, the nose is the issue in the AR's,
that is the focal point specifically the part right in front of the front drive band.
 

popper

Well-Known Member
I doubt you have much over 30 BHN, need a rockwell tester to validate that. I have shot boolits that dent superhard which is supposed to be 36 or so. Sized ~0.0005 above groove. My testing has all been 30cal, 22 is much more difficult. Boolit dimensions make variables more critical. Plus higher pressure is requires to get the needed FORCE. They work - commented that hard boolits will retain any deformities they get when in the barrel. Heavier boolits almost have a better BC/SD. More Sb is not the answer, but Cu/As or sulfur will help. I'll dig through my computer to see if I have targets and data for what I shot.
I tried posting what I think are basic 'rules' accepted by a LOT of testing by the casting crowd over many years in many guns.
 

popper

Well-Known Member
SCN_0105.jpg
Found it, lower right is HiTec coated 31-142C PB, all are from same mould. Others are HF red PCd. 16.6 load chronied 2150 avg from 1:10 18" BO AR carbine, Nikon 24x scope. The % is Cu, NO tin, higher %, harder, alloy is 4% Sb. Don't remember what the 2 middle bottom were, this was couple years ago. Probably 1% with coated nose. Loads worked so no further testing. 17gr H110 is ~1gr below 100% fill. Oh, LC 223 cut down brass, neck turned and CCI SRP.
I've never shot a 223.
 
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F

freebullet

Guest
The Lee hardness tester comes with a pamphlet, it's available in a free pdf.rps20181114_170635.jpg
Now, many here including me, would dispute that information to some extent. It does however show an interesting correlation.

It's all a balance & we can't have 2k+fps gallery loads that function semis, thats an oxymoron. h335 is a great powder for 223, we use it a lot. Our gallery loads use tightgroup, & get shot from a bolt gun @ less than 1200fps.

Maybe the image sheds some light on why your hard bullets are currently the seemingly best performers.
 

fiver

Well-Known Member
I'm sure you can follow it and have success, hell you can follow any 2-3 rules you want to and have success.[of some sort]
the problem here is he ain't having any success.
 

Pistolero

Well-Known Member
A really smart bullet guy once told me that "fit is king". He was right then and is still right.
.226 is in the direction of goodness, very likely. I have had very good results with .300 BLK
in an AR subsonic - 240 gr SMKs, but I bet that PCd would do similarly. Of course .30 cal
is not .22 cal, ever. But I just wonder if 4227 should be ignored.

Bill
 

Intheshop

Banned
Don't know diddly about AR's.

But the learning curve can be compared to walking my new shopdog. We both are travelling 3 miles if you look at it door to door. But she,being a puppy where everything is new,exciting,must go **** with it........ she's walking 3 1/2 miles.

This is perfectly natural......wouldn't want it any other way.
 

Bret4207

At the casting bench in the sky. RIP Bret.
Yes, Bret, it's an abstract concept. Best way I can explain it is comparing water-quenched WW alloy to Linotype. Same BHN, at 22-24. TOTALLY different behavior in a rifle barrel, or when placed on an anvil and clobbered with a hammer.

I've always said I can take 3 really different alloys and get you to the same BHn or take 3 examples of the
same alloy and get you 3 different BHn's. BHn is just a relative number, nothing more, nothing less. Those that can explain what the different components do when combined are up into Cast Bullet PHd level stuff.
 
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Bret4207

At the casting bench in the sky. RIP Bret.
As far as sizing, I've been using a Lee push-through .225" sizer to size once right after casting, then to seat the gas check, and finally to size one more time after PCing. Micrometer confirms .225" actual bullet diameter. I think bumping it up another thousandth or so might give me a little bit better fit, so with this batch I did not size after PC. Mics out to .226" actual diameter now. We'll see if that helps.

Just a thought, every time you size you're running the risk of deforming the bullet if it isn't going in straight, and 22's are tough to do no matter what. What is the reason for sizing before adding the GC? Also, have you checked the mic against a standard?

How are you crimping these bullets? Have you ever measured one pulled from a fully loaded case?
 
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