Twist Rates

B

baddarryl

New member
Hi all. Just as you need a faster twist rate to stabilize heavier bullets do those same rates work with lighter bullets? I am thinking .223. Say I have a 1:8 or 9 twist for larger 77 gr bullets will it shoot 36 gr as accurately as say a 1:12 twist rifle? All other things being equal of course. Thanks.
 
Yes, the twist rate works both ways; usually the lighter (shorter) < 45 gr bullets will be more accurate with the slower 1:12 twist than they will with the 1:8. I had a Ruger varmint bolt action carbine with a 1:12 barrel; 62+ grain bullets shot very poorly, 55grains were okay but it was a tack driver with WWB 45gr hollowpoints. The same loading showed well below average accuracy in a 1:9 AR rifle (as does .22lr 36-40gr ammo from a conversion kit).

Nothing is absolute though, other factors like velocity, bullet shape and composition, barrel length, etc can affect real world performance. It's often worth a try, as sometimes a bullet/barrel combination works out better than expected.
 
My Ruger (1 in 9) loves 65 gr Sierra GK's and 40 gr Nosler BT's. But I guess it varies to some degree from rifle to rifle. Of course that was the old barrel. The rifle and new barrel aren't back from the gunsmith yet.
 
tc encore with 27" MGM heavy factory barrel in 22-250ai with a 75gr amax and a charge of superformance goes .1" at 100 yards. a 1in8" is required:D
 
okay...hold on. if you guys are saying that a 1:12 twist will shoot a 45gr bullet just the same as a 1:7 twist. but the 1:12 will not shoot the75gr like the 1:7.....then why on earth would any manufacturer on earth still run anything but a 1:7 twist??? I have thought all this time that a slower twist will be more accurate" with a low grain bullet than a fast twist...... the fast twist exacerbating the bullet imperfection of a lighter bullet. hence the whole purpose for a slower twist .223 barrel to shoot lighter varmint bullets. I swear I have read this in several different studies of rifle twists in ar's

so why, then would any company make a twist slower than a 1:7 or 1:8?
 
skizzums said:
okay...hold on. if you guys are saying that a 1:12 twist will shoot a 45gr bullet just the same as a 1:7 twist. but the 1:12 will not shoot the75gr like the 1:7.....then why on earth would any manufacturer on earth still run anything but a 1:7 twist???
Click to expand...
I don't see anyone saying that here, but maybe I'm missing something.

skizzums said:
I have thought all this time that a slower twist will be more accurate" with a low grain bullet than a fast twist...... the fast twist exacerbating the bullet imperfection of a lighter bullet. hence the whole purpose for a slower twist .223 barrel to shoot lighter varmint bullets. I swear I have read this in several different studies of rifle twists in ar's
Click to expand...
It's technically a longer bullet, not a heavier bullet (though the two often go together). I'm not sure what you mean by "the fast twist exacerbating the bullet imperfection of a lighter bullet", though. A fast twist can sometimes spin a lightweight bullet so fast that the jacket comes off, but usually it's just a little less accurate than a slower twist would be.

All of this is covered in the sticky thread I referenced above.
 
kraigwy said in the Sticky:

What I take from John's charts, as well as the Army's, is that fast twist shoot light bullets better then slow twist shoot heavy bullets.
Click to expand...

I for the most part in my elementary understanding now understand it to be that way. It seems like the faster twist barrels will have less than of a negative impact on the lighter bullets than the slow twist ones will have on heavier. Unless one is shooting really heavy bullets specifically it seems like the 1:9 is the best of all words in my mind at least. Am I wrong?

Varmit 1:12
All purpose 1:9
Target 1:7
 
There's a good article about twist rates and accuracy in one of my Varmint magazines. Very interesting. I'll try to summarize their major points. A slow twist, as we all know, will stabilize small (short) bullets. That would be 1 in 12 or 1 in 14. The 1 in 9 was considered to be the best 'general' twist for 35 to 70ish gr bullets. I don't remember what they said about 1 in 8, but they did say that going to 1 in 7 or 1 in 6.5 was mainly for the folks shooting long range with specialty bullets of up to 90 grains. So, if shooting a range of bullets from 35 to 70ish grains, you are good with a 1 in 9 twist. If you need to shoot somewhat heavier bullets, go with the 1 in 8 twist. Seems like most rifle makers go with a 9 twist or an 8 twist, so it appears that they are well aware of what works with those twist rates.

The above is just a rehash of what I read with great interest. There are probably folks among us that can speak from actual experience and greater detail.

My new 223 barrel, which I hope to have in my hands soon, will be a 1 in 9 twist. If I had any intention to shoot bullets in the 75 to 77 gr range, I would have gone with a 1 in 8.
 
Also, a fast twist barrel tends to run hotter than a slower twist barrel. I would prefer the slower twist when multiple shots are needed.
 
The 8 or 9 twists are middle of the road and give pretty decent results with a wide variety of bullet weights. 7 and 12 twists are more specialized, but if you are going to err one way or the other faster twists will shoot light bullets better than slow twists will shoot heavy bullets.

I don't plan to ever go below 55 gr and as a rule shoot 60gr or heavier. 1:7 is what I prefer. It is still decent with 50 gr bullets, but would probably not do well with anything lighter.
 
I didn't start out planning to shoot 40 gr Nosler BT's, and actually had plans to shoot pigs with 65 gr Sierra GK's or 60 gr Partitions. But, it turned out that most of the shooting with that rifle, other than paper, was in the pastures around the house. I decided to go with a bullet that would destruct easily and not ricochet, so I tried out the 40 grainers. I don't think I'd use it on a pig unless I had no other choice, but when I used it on the first coyote I was stunned at how fast he went down. Same with the second one. Just knocks them flat. They didn't even twitch. All I can figure is that the bullet must dump all its energy into the coyote and not on the tree on the other side of the coyote. With the rifle now at a gunsmith for a fancy new super duper barrel (just because), I've gone back to my 220 Swift and the 55 grainers. I swear that the Swift doesn't kill em as fast as the 223 and those 40 grainers. Of course, there's much more testing to be done.
 
The 8 or 9 twists are middle of the road and give pretty decent results with a wide variety of bullet weights. 7 and 12 twists are more specialized, but if you are going to err one way or the other faster twists will shoot light bullets better than slow twists will shoot heavy bullets.
Click to expand...
Isn't it the other way round :confused:
 
"A bullet that's spun too fast for its length is better than a bullet that's not spun fast enough."

It might be better to phrase it, "A bullet that's spun faster than necessary for its length is better than a bullet that's not spun fast enough." IMO, less confusion for a newbie. :)
 
I used to be stuck on 1:9 because of varmint hunting.

After reading the sticky I'll get 1:8, 1:7 whatever I can get at the best price
 
Both of my 1:9 twist semi auto rifles shoot 75gr Hornady Superformance Match 75gr BTHP accurately and without issues at 100yrds. They both shoot 45-50gr accurately as well. I load 53.55.60.65gr for them both with the 60 and 65gr being the most accurate. I do like the Hornady 75gr a lot though.
 
I am using all 1:7 on my .223 builds now. I have seen no loss of accuracy on light bullets compared to 1:9. Give up just a smudge of velocity, but not a significant amount.
 
You must log in or register to reply here.
Back
Top