34gr Bullets in AR?

I'd sure want to know the loaded dimensions relative to the chamber (proabably lots of leade) and I should think a fella would want a very slow twist that's hard to find in AR barrels anymore. Those old 1:12s with Stoner barrel extensions aren't too common these days outside of a custom turn.

I think, anyhow. No reason not to give it a try though if the projectiles can be counted upon to remain available and cheap.

I mistakenly bought the 36 gr varmint grenades for my AR. I loaded them and they cycled fine, but accuracy was poor... as my twist rate wasn't right for light bullets.

The "twist isn't right" thing is a myth. The only problem I've had with bullets not shooting well, particularly frangible hollow points, in an AR is them getting damaged by the feed ramp when they are chambered.

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The "twist isn't right" thing is a myth.

Huh? Sure, twist matters. As an example, I have two bolt guns chambered in .223. The 1:12 twist eats up a 45gr HP like there's no tomorrow. No matter what I did with the charge, I couldn't get my 1:9 to digest it accurately. Worked my way up to a 60gr HP and Viola! All was right with the world again.

Is there a somewhat forgiving "window" of overlap? Absolutely. But to say twist is irrelevant is nonsense. Also consider why the twist rate of an AR was changed to 1:7. Stabilization of the tracer round. Previous twist wouldn't do it. So twist obviously matters.

"twist isn't right" thing is a myth.

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Please clarify. Either your grossly wrong and misleading or your words didnt correctly express your thoughts.

My reloads using the 36 grn Varmint Grenades worked well in both carbine and Mid-length guns. Couldn't really check for accuracy. I kept my shots to under 50 yards using iron sights and hit everything I aimed at. Both guns cycled fine and had no problems.

As long as the powder load is sufficient, the bullet weight is largely irrelevant to cycling.

Anybody that thinks the twist rate in relation to the bullet weight has no effect on accuracy needs to 1. read a book and 2. try it themselves.

Ignorant comments on a public forum that have no intellectual backing are only mislead those that come hear looking for solid information. Not very High Road-like if you ask me.

wgaynor said:

Anybody that thinks the twist rate in relation to the bullet weight has no effect on accuracy needs to 1. read a book and 2. try it themselves.

Ignorant comments on a public forum that have no intellectual backing are only mislead those that come hear looking for solid information. Not very High Road-like if you ask me.

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Point to a book with a credible author that states that spinning a quality bullet faster than the minimum required to stabilize is is detrimental to anything other than pure benchrest accuracy where the difference in measured in thousandths of an MOA. Bryan Litz devotes an entire chapter to this exact thing and his conclusion is that "over-spinning" a bullet is bunk. There is an article in the latest issue of Handloader saying exactly the same thing.

Now if you want the full disclaimer, here it is: If the bullet is a poorly made, poorly balanced hunk of metal, spinning it at all will cause a wobble and spinning it faster than needed to get it to fly nose forward will exaggerate the wobble and affect accuracy. However, such a bullet is going to shoot so poorly to begin with that you're talking degrees of suck at that point like 3 vs 5 MOA. Quality bullets need to be stable. Once that point is reached, the difference in accuracy from spinning any faster is so miniscule that it can't be discerned from the noise of normal shot to shot variations.

I've had good success shooting 36gn Varmint Grenades from a 1:9 bolt gun but less success from ARs unless single loaded. The reason is that the meplat of the hollowpoint has a tendency to get mangled coming up the feed ramp and upsetting the balance of the bullet. I've had similar problems with several different ARs in several different calibers. The rate of twist has nothing to do with the issue.

Pick any of the loading books you want for this information. I'm not going to type a book out on this forum.

Twist rate has a direct correlation to accuracy when factored in with bullet weight. That is why a 1:7 twist .223 does well with 50 grain and higher bullets but poorly groups anything less. A 1:12 twist .223 does better with the 50 grains and lighter bullets.

http://www.chuckhawks.com/rifling_twist_rate.htm

Chuckhawks saved me from typing out a book word for word. It gives you the basics.

Read through your post carefully, think about the implications of every word and sentence. You'll find that you contradict yourself.

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minimum required to stabilize

So we agree that every bullet has a minimum rate of spin for stability.

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"over-spinning" a bullet is bunk

What part? The part where it adversely affects accuracy? Or what about not spinning it fast enough?

You do realize that claiming no effect is flying in the face of both decades of balistic science and the experience of everyone who has ever worked up a load for a rifle, don't you?

I guess if the OP was shooting at a max distance of 25 yards, he wouldn't see the effect of not stabilizing the bullet enough.

Besides the potential accuracy issue, those lightweight varmint bullets are generally constructed to rapidly break up on impact. For varmints, that's good. If considering for SD, it's not good.

And, reliable cycling may depend on the gun & load in question. I've had no problems with weights in the 40s cycling ARs, but I've never gone down to a 34.
Denis

wgaynor said:

Pick any of the loading books you want for this information. I'm not going to type a book out on this forum.

Twist rate has a direct correlation to accuracy when factored in with bullet weight. That is why a 1:7 twist .223 does well with 50 grain and higher bullets but poorly groups anything less. A 1:12 twist .223 does better with the 50 grains and lighter bullets.

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I've never seen anything to that effect in any loading manual that I own, and I own most of them that have been published in the last few years and I've read them all cover to cover multiple times.

How about quoting the part in the Chuck Hawks article where it talks about spinning a bullet too fast? Since that's what we're actually talking about...

Stability is not a matter of accuracy, it's a matter of utility. An unstable bullet doesn't lack accuracy, it is simply is useless. If you you point out where in the discussion of shooting a light, short bullet in a fast twist barrel it would be logical to assume that spinning a bullet at a rate insufficient to stabilize is part of the discussion or even relevant, or where I've even implied that *insufficient* spin isn't a factor I'll gladly say I was wrong. But I've never said it, it isn't relevant to the discussion and isn't even up for debate. If I erred at all it apparently was in assuming that this much was completely understood.

The question at hand is whether spinning a bullet faster than the minimum required for stability is detrimental to practical accuracy in the real world. The answer, from those that have made a living at this stuff, is "NO, it doesn't make a difference". Again if you can cite a credible scientific source to the contrary...Here's two that agree with me:

1) Applied Ballistics for Long Range Shooting Bryan Litz
2) "Rifle Bullet Stability" John Barsness, Handloader #281 December 2012

Plus, the 34 grain bullet is as light as the common .22lr. Granted, the construction is different and the bullet is pushed twice as fast, but it's a small projectile. I'd prefer the heavier weight 62 grain of any construction over a 34 grain varmint bullet.

By the way, I wasn't quoting anybody.

You are still contradicting yourself. I won't push the issue with you anymore on this. Peace.

Quote Helotaxi: "practical accuracy in the real world".

I suspect that's the root cause of your disagreement with some of the members here. I don't know your definition of "practical accuracy", but if it is the same as the more often used term "battlefield accuracy", then for you, at least, rifling twist rate is close to irrelevant.

Many of the rest of us are here because as target shooters - not soldiers - we're not satisfied with the grotesquely inadequate accuracy of factory ammo. That is why we go through so much work to create an accurate cartridge for our particular rifles. When accuracy is defined by tiny groups, rifling twist rate becomes very important.

If your primary concern is hitting an IPSC target at intermediate distance, then rifling rate of your rifle can probably be ignored.

Back to the original question reagarding 34 grain bullets in the OP's AR rifle:

I experimented quite a bit with various loads in my JP CTR-02 with a 1/8 twist 20" barrel. While gathering data to determine the limits of this rifle, I shot some 40 and 45 grain Sierra and Hornady HPs, and about half did not make it to the 100 yard target - they disintegrated after leaving the barrel.

However, these loads performed very well in a 1/12 rifled 22" AR.

IMtheNRA said:

Quote Helotaxi: "practical accuracy in the real world".

I suspect that's the root cause of your disagreement with some of the members here. I don't know your definition of "practical accuracy", but if it is the same as the more often used term "battlefield accuracy", then for you, at least, rifling twist rate is close to irrelevant.

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Actually I'm a target shooter myself and I'm talking the difference between 1/4 MOA and 3/8 MOA. That's a negligible difference in the real world. By "real world" I'm talking about varmint shooting and shooting for score, not benchrest group size.

wgaynor said:

You are still contradicting yourself. I won't push the issue with you anymore on this. Peace.

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Where? Seriously?

Bullet length is what matters, not weight. The two are obviously closely related, but are not absolutely interchangeable.

FWIW, 34g Varmint Grenades shoot pretty well out of my 1/8 AR - but they are very long for their weight.

Real world experience. A faster twist can not only destabilize the bullet, but actually make it tumble. I tried loading some 55 gr Nosler SHOTS bullets in my son's Stevens .243 Win with a 1 in 9" twist and it couldn't keep them on the target board at 100 yards. One of them did hit the paper with a perfect silhouette image of the 55 gr bullet - sideways on the paper! These same very short bullets shoot less than 2 inches out of my 1 in 10" twist Sako A-7 and his girlfriends Ruger .243 with 1 in 10" twist. I won't bother experimenting with some 73 gr A-Max bullets in my 1 in 12" twist bolt guns, don't want to waste the bullets. I also have a Howa 1500 in 6.5x55 Swede. I am not exactly sure if it is a 1 in 8" or 1 in 9" twist, but it will NOT group any bullet that weighs 100 grains or less. I am talking about 7 or 8 inch 3 shot groups at 100 yards off the bench. So base on my personal real world experience, twist rate does matter, no myth, just fact. FWIW. This is America, everyone is entitled to their opinion, even if they are wrong. How else could the president have been re-elected?

Chances are good that those SHOTS bullets were coming apart from the velocity not tumbling from twist.