Originally Posted By CJan_NH:
Originally Posted By Invalid:
If you bought a 1-7" twist barrel, that's well and fine, but I think there is nearly ZERO need for it. Unless you bought your AR just to emulate GI Joe, the "other" use for it would be as a varmint rifle. The absolute heaviest varmint bullet available to handloaders in .223/5.56 is 60 gr. Otherwise, you're most likely to use the cheapest ammo you can find, for range blasting. This typically comes in the 55 gr. flavor, with Russian Steel cased stuff available up to 62 gr.
I have a 1-9" twist barrel, ON PURPOSE. I have seen bullets disintegrate in flight, when I was a range safety officer at the Lee Kay Center, in Utah. The guy was shooting a .257 Weatherby, with factory ammo. At first, we couldn't figure out why there was no impact at all on the 100 yard berm. After a few shots, I noticed that each time he fired, there was a fresh black line in the snow, extending about 30 feet in front of us. There was no-one else around, so we moved over a coupla' lanes, where the snow was virgin in front of the bench. Sure enough, it kept happening. I don't know if he had had the rifle rebarreled, or what.
My point is that if you intend to use your AR with varmint bullets, the slower twist makes far better sense. The jackets of quality varmint bullets are thin, by design, and there is a limit to how fast you can spin them before they disintegrate in flight. That difference between 1 turn in 7" and 1 turn in 9" seems small, but a little bit of math is very revealing. Figure the same bullet, covering just 6 feet (72 inches), regardless of velocity. The 1 in 9" twist spins 8 revolutions, and the 1 in 7" spins just over 10. That's 20% faster. If you wanted to use something like the Speer 52 gr. HP, you could expect to reach about 3,200 FPS from a 16" barrel. With a 1-9" twist, I think you'd be fine, but with 1-7", I think you'd have to keep a close watch over the disintegration problem, and maybe drop velocity a bit to control it.
I'm sorry for singling you out Invalid, but a couple of observations need to be made:
1) Someone who defends 1:9 always uses the line "just to emulate GI Joe" when discounting the utility of a 1:7 barrel. It's as dependable as death and taxes. Why is that exactly?
2) The heaviest bullet available to handloaders that is readily available on retail shelves is the Hornady 80gr A-Max
. The OP didn't mention varmint rounds at all in his post.
3) Many of us who have ARs tasked for defensive use prefer heavier OTM rounds like 75gr Hornady TAP
or Black Hills 77gr Sierra
in our defensive weapons. A 1:9 barrel may or may not
stabilize those heavier rounds. Of the eight 1:9 barreled ARs I currently own, six of them handle the heavy stuff fine and two do not. That's a 25% failure rate-just in my personal collection.
4) Most surplus or cheap plinking ammo is 55 to 62gr, and 1:7 handles that just fine. Test after test by members here has demonstrated that there is no appreciable difference in accuracy between 1:7 or 1:9.
My two safes are chock full of 1:7, 1:8, 1:9, and 1:12 ARs, a couple of 1:7 Sigs, and a few other oddball rifles. There isn't a round I can handload that won't work in my 1:7 ARs and Sigs, but there are
rounds that won't work in my 1:9s and 1:12s. With that in mind, 1:7 (or perhaps 1:8) is the most versatile for me.
When I buy reloading components I do so twice a year, and in a group with several other people. We decide what we want and combine our resources for quantity pricing. One year we decided to buy 40gr Noslers because my buddies out west were big into prairie dogging-I ended up with 11,000 of the damn things
There is no way in hell I would have taken part if I didn't know up front that they would work. I'm about 8,500 rounds into that 11k, and the only problems I've ever had were due to a light crimp-the 40gr Noslers don't have a cannelure. I load those 40gr bullets on top of IMR 4198, and I load them HOT.
Never had a problem with fragmentation/detonation/keyholing in any of my rifles
Oh, and per the video above, a lightweight V-Max...really? That's
what you're going to use to "prove" your point. Come on man
In closing, even if I didn't reload-the likelihood of me needing to shoot a heavier bullet is far greater than my need to shoot a varmint bullet. For that reason, 1:7 or 1:8 is the most versatile in my book.