Incorrect Barrel Twist

[BigN]

Seeing how the twist on my 223 is 1-9, I loaded up some 69gr Sierra HP and headed to the range. I shot 3 rounds and never hit the paper at 100 yards. With no way of knowing where the round was hitting, I moved the target up to 50 yards. The next round hit over a foot low and a foot to the left, sideways. I shot several more times to confirm and the bullet was ripping a 2" slit into the paper. I stopped shooting those rounds and when I got home I pulled all the bullets. I got the twist rate directly from the factory, but after seeing the results of the 69 grainers, decided to check it myself. Sure enough, the twist was actually 1-12, apparently not fast enough to stabilize the heavier bullets. Seems like back in the olden days, all my guns had the twist rate stamped into the barrel. Nowadays, not one of my 50+ rifles have the twist rate stamped into the barrel. Is this a dying art or are there more specific reasons for not putting the twist on the barrel anymore. Seems to me it's as important as putting the serial number on it. Wouldn't it make things much easier if they continued to do this?

 

[loadedround]

I ran into the same problem with my Colt H-Bar with a 1/7'' twist and 55 gr bullets several years ago. I feel your pain and suffering until I wised up and used a heavier bullet. My little Colt just loves those 69 grainers. Stick with the 52-55 gr bullets and you'll be very happy.

 

[ranger335v]

I'm 70 and I've never seen twist rate stamped on any barrels at all. It's so easy to determine I never even thought of it. ??

 

[cougar1717]

IMHO, I think most manufacturers do not imprint the barrel with the twist rate due to cost and redundancy. To be really honest, there's only a few calibers where the twist may not be able to stabilize a long for caliber bullet: usually in .224 or .243 calibers. For most other calibers, the accepted twist range is already pretty standard. For instance, in .277 and .308 calibers the twist is usually 1 in 10" or 1 in 11"; 7mm calibers may be a little faster at 1 in 9.5"; .264 is usually long for caliber and needs 1 in 8". The only time we really hear about tumbling bullets is trying to shoot 100+ gr .243 dia bullets out of something that's 1 in 10+" or your situation - shooting 60+gr .224 dia bullets out of something that is 1 in 12+".

 

[dbarnhart]

you should be able to shoot up to about 62gr bullets with a 1:12 twist barrel.

 

[Strykervet]

That was the first rifling use in the M16 wasn't it? They changed it when they went to 62 grain bullets because of this very problem didn't they?

I have a 1/8 twist, sort of the jack of all trades, and it will stabilize the 75gr. Hornady T1 just fine. Very accurate too.

The flavor of the day is to use heavy bullets in 5.56, so I bet there will be problems in some of the older rifles that have this twist.