1/9 vs 1/7 twist?

[CZguy]

You aren't generally correct - you aren't even half-assed correct. You are so far from correct you couldn't see it with the Hubble telescope. So I don't really see it as nit-picking to point out that the Earth is not flat nor is the Moon made of green cheese.

Well now that the science of it is clearly established I wonder if he will be a big enough man to apologize.

 

[PlayMaker]

Quote:
Get a 1/14 if you want to duplicate the wound channels that the 5.56 was famous for creating back in the day. Anything less than 1/14 and you lose the tumble and the bullets zip through like butter.

You don't know what the hell you are talking about. There isn't a rifle made with a twist fast enough to stabilize a 5.56x45 bullet in tissue.

I was thinking the same thing.

 

[vanfunk]

What? Try shooting 45-50gr loads out if a 1 turn in 7" barrel....

I have, and do, routinely, with no problem.

The 40 grain Sierra Blitz is known for coming apart upon leaving the barrel at 3600 fps, but other than that rather odd example, this is a non-issue. Even those WWB 45 grainers are no problemo, and 50 grainers? I've never, ever heard of a 50 grain bullet coming apart in a 1/7" twist barrel when pushed to 5.56/.223 velocities. IMO 1/7" is the way to go.

vanfunk

 

[PvtPyle]

The boat tail has nothing to do with the reason, or way that the 5.45X39 round tumbles. You are not even in the right ballpark. It is the NOSE of the round and the hollow air cavity and weighted section immediately behind it that makes the round tumble.

I shoot the 77gr in my 1/8 with amazing results. It is the same barrel and bolt used in the Army's MK12 sniper rifle, and it does exactly what that one does. But I also shoot the 77gr out of my 1/9 10.5" with the can and it provides devistating results on soft tissue and is accurate out to 100m. Most of the time I shoot green tip, but for the defensive stuff it is the 77gr. I need to chrony it and see what speeds I am getting.

HK Guns, your information is generally flawed and your understanding of the way it all works is somewhat lacking. Instead of argueing I would try reading more. If you have contrary info, I would not stand up and say "Nuh-uh! Momma say aligators are mean cause they gots all them teeth!". Instead try presenting your info with a source and let it be compaired. But calling out someone with a significant amount of experience more than your generally makes you look foolish. Read more, write less.

 

[DoubleTapDrew]

So shooting through a 1/7 isnt going to do anything "magical" like spin the round so fast it sheds the jacket?

That's the thought going through my mind as well. Will shooting light bullets in a 1/7 cause one of those neat trails that doesn't make it to the target?
My AR is a 1 in 9 so I picked up some match kings in 69gr. I'll have to load them up and see if it will work ok. I figured anything heavier than that wouldn't stabilize. I'd like to build a 1 in 7 gun though for more options if it'll still shoot 55gr ok.

 

[RockyMtnTactical]

So shooting through a 1/7 isnt going to do anything "magical" like spin the round so fast it sheds the jacket?

It can.

Something to consider is this. Not all 1/7's are the exact same. There are variations. One may be closer to being a 1/8 and one may be closer to being a 1/6. Individual barrels shoot different from others that are marked with the same twist rate.

 

[SpeedAKL]

I just learned more about 5.56mm bullet performance in the last 5 minutes than I did the entire rest of the year...