Bullet weights for 1:9" twist barrels

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deerslayer303

New member
Looking to get some feed back from those of you who have AR's with 1 in 9 twist barrels. My upper is a Stag SH 1:9 chrome lined. The guy at PSA told me to stick with 55gr. bullets as they perform well with this twist rate. Have any of you shot heavier bullets with a 1:9"? I'm not planning to shoot no more than 200yards max. As always I appreciate your time.
 
It depends on your "actual" twist and your barrel length.

Some 1/9 are really 1/8.75 and can stabilize heavier bullets.

If you have a long enough barrel (and can get the bullet going fast enough) a 1/9 can stabilize longer bullets.

Unless you are using a suppressor, buy a box and give it a try. Worst thing that happens is the bullets are unstable and they keyhole or shoot all over the paper. Embarrasing if you are trying to shoot in front of your buddies but nothing that will damage anything.

If you are shooting suppressed, don't do it. You could get baffle strikes.:(
 
In my experience instability due to excessive bullet weight (length) for a given twist doesn't show up until about 200 yards. And even if closer only shows as slightly larger groups... not keyhole shots.

Has anyone actually had a round tumble or wobble in a silencer/moderator? I find that hard to believe.
-SS-
 
For an AR it is not so much the bullet weight but the bullet length. The max OAL for a AR is 2.260 that is the longest OAL you can use and still have the round fit in the magazine. Without issue the 55 grain bullets will generally be at 2.200 OAL and you should be able to get the 60 grain bullets to 2.250 OAL. Beyound that the 62 grain will fit as will some 69 grain bullets, but it is really up to the individual bullet and it's length.

You do not have the same issue with a bolt action rifle since the internal mags are a lot longer. I use a 75 grain A-Max in my bolt action rifle that also has a 1:9 twist and stabilization is no problem.

So your consideration should be "What OAL does the bullet have to be set to".

Jim
 
I have not personally experienced a baffle strike due to bullet wobble.

I have read about it from some guys I trust. However, they were using 11.5" barrels and 77gr bullets which probably exacerbates the wobble. (Even less velocity and spin on the bullet than a 16" 1/9)
 
"In my experience instability due to excessive bullet weight (length) for a given twist doesn't show up until about 200 yards. And even if closer only shows as slightly larger groups... not keyhole shots."

Shooting bullets over 55g in a ChiCom AK in .223R I could not even come close to the target at 100 yards let alone 200 yards.

Moved to 25 yards and even at that range there was evidence of the bullets wobbling and huge "groups".

At 50 yards bullets were actually tumbling and you could no longer consider the result "groups".

T.
 
i am a reloader with over 50 years experience, i have loaded every weight bullet available in .224 caliber, i have used about 18 different powders and maybe 12 different primers fired many different combinations of loads, considering bullet weights only there was very little difference in any groups at 100 and 200 yd. fired from Colt 1-7 and 1-9 twist barrels.

and.., yes, i saw a "can" take an internal hit from a bullet fired from a .308/7.62X51, some witnesses said the "can" was not screwed on properly, others said it was bent, (cross thread?) shooters reported an extra loud bang, whatever.., it was a messss.
 
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