Ways to consistently increase pressure for gallery loads

BHuij

Active Member
So I have run into the problem of "not enough pressure for efficient or consistent burn" a few times as I've worked up light loads for various firearms, especially rifles. This most commonly happens when I'm working well below the reloading manual recommended minimum powder charges for jacketed bullets. It appears to be more severe with slower powders than faster powders, presumably because pistol powders more quickly reach "optimal pressure" for a good burn than rifle powders (side note; is this why magnum pistol powders are often used for mouse fart loads in milsurp rifles?)

Inconsistent and inefficient burns lead to inconsistent velocities which = vertical stringing. Also can lead to really dirty ammo which can be problematic with direct impingement gas guns like ARs, although that particular problem hasn't affected me (yet).

So there appear to be three traditional solutions to fixing this problem:

1. Increase the charge. Obviously this isn't super viable if your goal is a light gallery load.
2. Use a faster burning powder. This is probably fine in bolt guns (indeed it appears to be the standard recommendation), but quickly leads to short-stroking in gas guns, particularly ones with mid- or rifle-length gas systems. I myself couldn't get IMR 4227 to cycle in my carbine-length .223 AR-15 with a 16" barrel without loads that had me worried on chamber pressure spikes (and weren't accurate anymore).
3. Use a filler such as Dacron.

Seems like with cast bullets, having too much pressure up front (i.e. too fast of powder) will deform bullets before they clear the parts of the chamber where there's room for riveting and the like, which leads to poor accuracy. If you can get the peak pressure to occur AFTER the bullet is well into the rifling, and your bullet design doesn't have a big honkin' bore rider or otherwise unsupported nose (looking at you Lee 185gr .312"), deformation can be kept to a minimum and you have one less thing trying to ruin your accuracy. Meanwhile, anything you can do to help the bullet resist deformation before fully engaging the rifling is a plus. Seating out as far as possible during loading, using a gas check, and maximizing the hardness of the bullet all seem to help. Indeed, my best and most accurate cast bullet rifle loads are all seated to the max OAL I can chamber, and use the slowest powders I have yet tried. Also my best results with cast .223 in my AR were bullets heat treated and measuring at a surprising 35 BHN.

So after all that rambling, I guess I have two questions:

1. Would increasing neck tension for the purpose of upping chamber pressure cause more harm than good? Seems like it could give me a more consistent burn with ball powders like H335 or slowish stick powders like IMR 4895, but also seems like it would increase the chances of having a pressure spike to deform the bullet before it's "safe" in the rifling.

2. Is there any reason not to shoot the absolute hardest bullets I can make in a high-pressure rifle round? I have gotten 35 BHN with HT/Q on COWW alloy and that performed better with the same near-jacketed loads of IMR 4895 than 26 BHN bullets. Only reason I've ever heard cited about too hard of alloy is failure to obturate and get a good seal in the barrel, but it kinda seems like the less obturation, espeicially at the base, the better shape the bullet will be in when it leaves the muzzle. The reason I ask is because I have about 20 different loads of .223 loaded up and ready for my next range trip, ranging from "probably won't cycle" to "hot jacketed load" territory. If NONE of them perform even with 35 BHN bullets, I want to look at trying out some weird stuff like adding babbit or copper to my alloy to exceed 35 BHN.

Oh, and bonus question, is there really no better option for modeling loads before physical testing than Quickload? Seems outrageously expensive for what it is.
 
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fiver

Well-Known Member
1 probably.
2 yeah there is.
BHN isn't the answer you have to have something in there to hold the bullet together besides a hard reading from a dent or punch.
crooked hard is still crooked...
3. not really.
there is experience which you gain by spending money and time and keeping notes.
or you spend the money up front and the time checking the results to well help make better predictions.
 

RicinYakima

High Steppes of Eastern Washington
The best option is to buy a bolt gun. The second is the load even lighter with faster powder and use the AR as a manual operation system, i.e. pull the charging handle every time. You are trying to make a race car pull a manure wagon through the mud. Sorry.

p.s. Auto loading firearms have very limited functional range, you want to go outside of it and it doesn't work.
 
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Intheshop

Well-Known Member
On neck tension....

JMO,or how I tend to look at things? Assuming you have a rig accurate enough to tell the difference? And the driver is up to the task.....

You need to be able to adjust neck dimensions easily and accurately because, each load/rig is gonna have likes and dislikes. The higher the tension, IME... the harder it is to keep runout #'s low using typical,over the counter dies. But higher grip can help in a cpl areas. Start pressures and trips up through a mag being a cpl more obvious.

There's a pretty long list of things going on with "fit" here.And it ain't just about cramming a CB up into the leade. The ability to change parts of this interface "easily" is one of the keys. The target is one gage.... on the terminal end..... having the ability to measure or gage the loaded round,during and after processing,starts to move to the forefront once you start chasing numbers or metrics.
 

BHuij

Active Member
1 probably.
2 yeah there is.
BHN isn't the answer you have to have something in there to hold the bullet together besides a hard reading from a dent or punch.
crooked hard is still crooked...
3. not really.
there is experience which you gain by spending money and time and keeping notes.
or you spend the money up front and the time checking the results to well help make better predictions.
So I get that BHN isn’t the whole story or the complete solution since my bullet fit is poor. But what do I gain by hardening to 20 BHN instead of 30, all else equal?
 

Bret4207

St Lawrence river valley, NY
What do you gain by hardening at all in the very light loads you're talking about? The whole idea behind "hard cast" is that lead alloys act just like copper alloys and since copper is harder than lead, it must follow that harder means less erosion, stripping, leading, etc. Except lead alloys don't act anything like copper alloys, so it doesn't work like that. It's apples and processed imitation "American cheese food". And then the same guys preaching "hard cast" tell you the bullet needs to obturate to fill the grooves...but you made it harder, so thats more difficult. Harder alloys have a place in higher pressure loads. But you aren't going for higher pressure, just the opposite. I'll confuse it even more and mention that "fit" has at least 2 elements to it- static fit and dynamic fit. Static is everything before you touch off the primer, dynamic everything after. So, take a gun that you are trying to make do something difficult to start with (even jacketed bullets in very light loads aren't going to cycle), try to use slower burning powders, start with possibly poor static fit and then add super hard cast bullets into the mix and somehow expect a BHn that tells you maybe half or less of WHY the bullet is harder to cure the issues in play? I'm not going to pretend to have the answer for you, especially in platforms I have no cast experience with (AR types), but I can tell you that "hard cast" isn't going to cure the problem. Deforming the bullet even more with heavy neck tightness and using inappropriate powders is about 180 degrees away from finding any kind of answer.

Best advice I can give anyone starting with cast- absolutely, totally, completely forget the term "HARD CAST" for solving any problems you have. It's a meaningless sales term that means as much as "NEW! IMPROVED!" does on soap or deodorant.
 

Brad

Administrator
Staff member
Light loads in an AR aren’t going to give good function. No filler, hardness, or anything else makes up for a lack of powder gas and appropriate pressure at the gas port. BHN isn’t gonna drive the BCG back.

Rick did accuracy testing that showed BHN isn’t all it is made out to be regarding accuracy. He found accuracy increased but only to a sweet spot and going harder gave worse accuracy.

Want a simple test to show how BHN can give troubles? Shoot some .002 undersized but very hard bullets in a revolver. Maybe 50 rounds or so. It also teaches you how to scrub out lead. Oddly a very soft bullet might not lead in this example as the bullet can essentially swage up to fill the bore.
 

Sig556r

Active Member
Try .300BLK upper in your AR carbine lower, it's designed for light loads on heavy projectiles unlike .223Rem where even 77g boolits has to travel around 2500fps or more to reliably cycle the action.
 

fiver

Well-Known Member
I will point you in a little better direction.

okay you have a hardness.
but think about your bullet like a house.
you want to move that house across the street.
now you could spray the whole thing down with 3"s of acrylic and let that harden.
then just pick up the corners of the house, or with a giant hook from the top and start on your journey.
you'll probably get there with a nice mold of what your house looked like.

now get you some soft pine boards,.
go inside the house and start bracing it across the walls, down the walls, across the door ways.
from floor to ceiling, and from wall to wall.
now jack it up and put some rolling logs underneath it then push it over there.

same thing accomplished.
your house is now across the street, only in one scenario you internally braced the house,
your braces had some flex and movement in them, and in the other you had nothing but a protective box around the outside.
you got them there by different methods two completely different methods.

what has this got to do with anything?
nuthin I just like using comparative story's.
 

BHuij

Active Member
Some weirdly angry replies here.

So I never used the term “hard cast.” My question here is whether a COWW bullet at 20 BHN (sized properly) might perform better in a given situation than a COWW bullet at 35 BHN would, all other things equal, and why. This is not specifically asking for an AR, just in general.

The reason I ask is this. Near as I can tell, resisting and minimizing deformation is the name of the game with cast bullet accuracy. There are other considerations once you have minimized deformation (like powder burn consistency), but static fit, dynamic fit, minimizing pressure as much as you can get away with, increasing bullet hardness, and trying to get the bullet into the rifling before reaching peak pressure are all means to this end of minimizing deformations. My experience has been that the bullet is easiest to deform before it’s through the chamber and past the throat, especially in a gas gun where you have to choose between perfect static fit and leaving enough looseness for reliable feeding and chambering.

So guess what I’m really asking is, given the fact that a higher BHN appears to reduce bullet deformation upon firing at ANY pressure in any gun, what reason is there to stop at a certain point like 20 BHN instead of going harder like 35 BHN? What have I lost by exceeding 20 BHN or whatever the “sweet spot” happens to be?

And to be clear since I’ve been misunderstood here a few times:

I do not think BHN tells me everything there is useful to know about an alloy. I do not think harder bullets are more likely to cycle a gas gun. I do not think high-BHN lead bullets are equivalent to FMJs.
 

RBHarter

West Central AR
The AR platform requires 15,000 psi at the gas port for function with GI parts .
You can reduce the buffer weight .
You can reduce the buffer spring weight .
You can enlarge the gas port and add an adjustable gas block .
You can get a pistol length gas 16" barrel , or have an existing barrel fitted as such with a blank gas block over the OM gas port .
Single or in good combinations will get you down to reduced loads .

Powders are a great way to spend hours figuring out why , what is happening .
Start jacketed data with slower powders and nominally heavy bullets works as a loose formula for me 90% of the time .
In 223 I shoot an alloy water dropped at 18 BHN pencil test NOE 225-55 @62 gr over H322 for 2080 fps in an 8" twist . Same bullet out of the 12" twist 222 goes 2600 so do what you want with that .

The problem with the full rifle tweeks is that you end up with a dedicated platform for those loads . Building a second upper with short gas and a light bolt carrier group for the light loads is the best bet .
 
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fiver

Well-Known Member
not so much resisting or fighting.
you want the bullet to accept the rifling without taking on any secondary damage in the process.

none of the answers were hostile.
it's kind of hard to explain why an alloy with twice as much tin/antimony works better.
but it's also one with half the antimony and the same amount of tin as another alloy that worked as poorly as the first one did.
it's similar to my bracing scenario above.
you have internal structure, but you also have the ability to ebb and flow with the changes the bullet see's in it's first 1/2" of movement.
 

Ian

Well-Known Member
15K psi at the port....PLUS adequate dwell time and fall rate. Narrow window indeed.

The name of the game with cast bullets is getting them into the bore straight. It's like figure skating, lots of force and mass flying around, precisely guided. If it isn't guided correctly, crash and burn. Can't force this stuff. Just making harder bullets won't make up for poor fit, in fact it makes things worse. Toughness, guidance, pressure rise, jump, all play a part.

My brain hurts after reading through all this, I really don't know what you want to accomplish. Why don't we start there? You want X load and bullet to do X job, what are the options for making it work?
 

Rick

Moderator
Staff member
No, no anger intended here by anyone. Just years of experience and testing proving that harder is rarely the answer to most questions asked about cast bullets. Truth is that too hard of an alloy is one of the most common causes of barrel leading and poor accuracy. With the reduced loads your looking for an alloy of 10-12 BHN would be the hardest I would consider. Has nothing to do with cycling the gas system in an AR, has to do with cast in general. For a gas gun to cycle it has to have a certain pressure at the gas port. Light bullets and fast powder won't do this, out of gas volume before it gets to the port. Slower powder with a heavier bullet could possibly get you there with reduced or somewhat reduced loads.

The term "HARD CAST" was coined by the commercial cast bullet industry for the simple reason harder bullets suffer less damage during shipping but it has nothing to do with how well they shoot or how good they may be for the customer. Same thing with commercial casters using hard lube, it's not for the benefit of the customer or that it even works well in most situations, it simply stays on the bullets better during shipping.
 

fiver

Well-Known Member
that would help.
but I wouldn't even bother trying for a lighter gallery load in an AR platform.
it either cycles and shoots or it don't.
I can buy 50gr. V-max's for cheap, heck I can make SMK's for under a dime.
gas checks are 3 cents.
 

Rick

Moderator
Staff member
BTW, in regards to your OP on NK tension: Rather than most likely deforming the bullet with too much NK tension a better approach would be slower powder and a heavy for caliber bullet. To burn well the slower powder needs the time to burn and rather than NK tension or crimp to do this which won't work the resistance of a heavier bullet will aid the slower powder in burning both better and more consistently.
 

Bret4207

St Lawrence river valley, NY
No angry replies have been made. Look, you start off talking about "gallery loads", which to me and everyone else I've ever read means a greatly reduced load meant for short range, often indoor shooting. Something akin to a 22 LR out of a 223, if that's what you're using. You start off with not wanting to use a faster powder, something more traditionally appropriate for "gallery loads", because you are concerned with not getting the action to cycle and because you fear deformation from the faster powders. Then you went on to wondering about increasing neck tension to the point that you get a cleaner burn with slower powders, yet that neck tension is almost certain to give a far greater chance you'll deform the bullet, even at 30Bhn. Then you get into super hard cast BHn numbers, but you aren't concerned with fit...or at least the way I read it you aren't.

Go back to step one. What do you define as a a"gallery load"? What cartridge and bullet are you wanting to use? How does that bullet seem to fit your rifle so far? Does the rifle seem cast friendly? Do you have a choice of bullet designs or are you stuck with one choice at this point? Have you worked on the fit of that bullet in that rifle yet or are you just going with a standard diameter and seeing what it does? You need to fill in some blanks before worrying about BHn. This applies to any gun, not just AR's and semi's.

As far as your question in post #10- If you take the same alloy that runs about 20 BHn (or 13 BHn for that matter) and treat it to get it to 35 BHn and change nothing else, there is no reason, based on my experience, to think it will perform any "better" than the softer example. But of course, by "better" I mean it will be more consistently accurate. "Better" is too ambiguous a term to use without more definition on what you mean by "better". If the load was shooting 1" 10 shot groups at 100 at 1500 or 2200 fps, how much "better" are you expecting? If the load was shooting 5" groups and filling the bore with lead after 10 shot groups, then maybe it would or maybe it wouldn't. It might cause the groups to open to 10", you don't really know until you add more info and try it with that gun, that powder charge, that brass/primer/lube/etc., which all comes into dynamic fit I guess the point I'm trying to get across is that BHn is just a relative number. It doesn't mean anything in itself as far as being an indicator of consistent improvement across the spectrum of cast shooting. I'm sad to say it just isn't that simple, but those selling the idea that BHn is an indicator of a "better" bullet (ie-HARD CAST) have done a fantastic job if getting that idea out there and ingrained into our heads.

And going back to your question on post #5- NOTHING. You gain nothing by going to a harder alloy or BHN if the fit is poor in the first place. Fit is king- period. If it doesn't fit, it's not going to shoot for beans regardless of how hard it is.

I try to avoid getting into these discussions simply because there are no easy, simple, work every time answers. At least not that I've found. It's why some of us maintain this is as much an art as a science. If you read any of this as angry, you are reading something into it I never intended.
 
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popper

Well-Known Member
Inconsistent and inefficient burns lead to inconsistent velocities which = vertical stringing. OK let's get back to your real question. Powder has a 'burn rate' that is somewhat dependent on the volume in which it is burning.
1) You get dirty brass cause the pressure isn't high enough to expand the case neck and seal the chamber.
2) With a slower powder you COULD jam the lands or hard crimp to keep the bullet from moving and allowing the volume where the powder burns, keeping it's burn pressure higher and where the burn rate is better. Do that at your risk. You COULD use filler or dacron to restrict the volume also - at YOUR risk.
3) you could use the proper powder as that is why we have tested load data from manufacturers.
4) auto loaders have a narrow 'window' of pressure that allows proper feed. Blow back or gas system the same. Gas volume at the port determines the operation - some powders create little volume - as they are designed that way.
5) vertical stringing is caused by velocity variations. Could be bad burn, inaccurate charge, bullet weight variation, bad ignition, etc.
6) hard bullets do NOT directly cause vertical stringing.
7) peak pressure to occur AFTER the bullet is well into the rifling That is the reason for slow powder burn rate. Shaped or coated powder by the manufacturer.
8) do NOT download 335 or most ball powders.
9) do NOT think that real hard bullets don't get deformed. But they do stay that way.

I use gallery loads in my AR but use pistol powder. Works just like a bolt gun. Even in a pistol port AR. It will almost cycle, probably would when I open up the AGB.
An interesting but off topic note: read a bunch of Fin/Swede/Norw. articles years ago about their 'training' gallery loads. Wood bullets, sometimes only a primer, very light loads. How do you train a militia on rifle shooting without the Germans hearing you. Or not using up all the good black market(?) ammo?
 
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Spindrift

Active Member
An interesting but off topic note: read a bunch of Fin/Swede/Norw. articles years ago about their 'training' gallery loads. Wood bullets, sometimes only a primer, very light loads. How do you train a militia on rifle shooting without the Germans hearing you. Or not using up all the good black market(?) ammo?
Sorry, not my intention to derail the thread. Yes, wooden bullets were used in norwegian Krag 6,5x55 rifles. I believe they were used to teach rifle shooting to school kids, they had shooting classes back then.
 

Bret4207

St Lawrence river valley, NY
Sorry, not my intention to derail the thread. Yes, wooden bullets were used in norwegian Krag 6,5x55 rifles. I believe they were used to teach rifle shooting to school kids, they had shooting classes back then.
Some years back you could buy that wooden bullet training ammo through the surplus outfits. I saw a box of it at a gun shop one time. Probably should have snatched it up as a conversation piece.