Twist Rate and Bullet Stabilization Problems

Technically it is bullet length that determines best twist. You might find that some bullets heavier than 55 gr will work while others may not. Within the same weight a hunting bullet will usually be shorter than the long aerodynamic high BC bullets used for target shooting.

If you can measure the length of some bullets you're interested in using you could plug the data into this to determine if it is going to be stable or not. Or you could select from the bullets offered by Berger. But they don't offer anything lighter than 70 gr.

Twist Rate Stability Calculator | Berger Bullets

jmr40 said:

Technically it is bullet length that determines best twist. You might find that some bullets heavier than 55 gr will work while others may not. Within the same weight a hunting bullet will usually be shorter than the long aerodynamic high BC bullets used for target shooting.

If you can measure the length of some bullets you're interested in using you could plug the data into this to determine if it is going to be stable or not. Or you could select from the bullets offered by Berger. But they don't offer anything lighter than 70 gr.

Twist Rate Stability Calculator | Berger Bullets

Click to expand...

I love some high BC super long bullets! that’s why 6.5 CM is so good, modern bullets

HowieG said:

I love long bullets in my 224 Valkyrie also, but part of the problem with that cartridge is it is/was heavily marketed as being a wonder with the 90 grain Sierra Match King. In fact, that bullet really needs a 6.5 twist barrel, but production rifles are mostly made with 7 twist barrels. This has led to people being not too happy.

Click to expand...

my A2 looking AR has a 20” barrel with a 1:9. I bought some 77gn super long tooth pick looking bullets for it. One day I will have enough time to shoot it

HowieG said:

My Valkyrie is a Savage MSR with an 18 inch barrel 7 twist. The heaviest bullets I have tried are the 80 SMK and 80 ELD. I have 77 grainers, but haven't tried them yet. The 69 Barnes Match Burner shoots extremely well and I have adopted that bullet for my tactical load.

Click to expand...

I think there is a Weight vs. Stablization table. I’m trying not to derail every thread

Mark_Mark said:

I think there is a Weight vs. Stablization table. I’m trying not to derail every thread

Click to expand...

It's not a weight issue, it a length issue, longer bullets require more spin to be stable at a given velocity. A bullet of a given length requires X rpm's to be stable, this is determined by barrel twist and velocity.

1:12 should be able to take up to 60grs.

1:14 may handle up to 55 grs, depending on ogive. I have a Savage 340 B in 222 (1:14) that will not stabilize 55 grs and a Savage Walking Varminter (1:14) that will stabilize the same 55 grs just fine.

HowieG said:

My big question, Doc, is have you actually measured both rifles yourself?? Do you know for a fact they are the advertised 14 twist??

Click to expand...

Yes. When the 55 grs same load would not work in both, I checked. Both 1:14

DocRock said:

1:12 should be able to take up to 60grs.

1:14 may handle up to 55 grs, depending on ogive. I have a Savage 340 B in 222 (1:14) that will not stabilize 55 grs and a Savage Walking Varminter (1:14) that will stabilize the same 55 grs just fine.

Click to expand...

Sure. Until it doesn’t.

This cannot be stated enough. More than any other caliber, know what you want to do, and what your limitations will be when you buy a 22 caliber centerfire rifle. Barrel twist is more important than rifle brand, in my opinion.

HowieG said:

Still I get what you are saying. All copper bullets screw things up because they are light for their length.

Click to expand...

The same with tracer rounds.

Like I posted in the last thread

Some rifles are picky.....others not so much.
Very fast twists are going to like longer projectiles, hence heavier with the added length. Which is not to say they won't shoot lighter bullets, but the results may be much less than acceptable.
Bullet construction is going to be a big factor, too. Lightly constructed varmint bullets like a TNT or a SPSX, will do better out of a slower barrel within their velocity limits. Put one in say a 1:7 at those same velocities, and those never make it to the target. Ive been to that rodeo, testing with a buddies AR and some 50 TNTs. 20" heavy barrel at about 3100fps, we'd hear a crack right after the report, and see a nice puff of smoke about 25-30 yds down range......that was the bullet, disintegrating. Pretty good physics lesson that day
How much throttle you put to em is also a factor.
BTW, my 22-250, 1:12, shoots most bullets well, from 40-60gr. 75 A Max....not so much. It does its absolute best with 55 VMax in my testing so far.
Lots of factors to consider, but in general the faster twists are gonna like the heavier, longer bullet, the slower twists will generally do better with the lighter, shorter.

HowieG said:

I had another gentleman on Highroad tell me that he was limited to 55 grain bullets or less in his 12 twist 22-250.

I am curious if anybody has personally measured the twist of his/her rifle barrel and found that it differed from what is published?

Also, does anybody have trouble stabilizing bullets that should work according to a reloading manual?

Can you please include what altitude you typically shoot at ?

Click to expand...

I've found my 1-12 22-250 will stabilize a 53 VMAX or 62 hpbt. Thus is the absolute limit for it.
At the same time. A 1-12 223 wouldn't stabilize a 55 fmj-bt.
It did great with a 55 fb or 52hpbt.

HowieG said:

Well, that's interesting isn't it? Same load I assume, but they surely don't chrono identically. Do you know which rifle is slower?

Click to expand...

Yes, the older 340B is certainly more worn and in all likelihood was less consistent to start with. So, it delivers the same load a bit slower (don’t have notes in front of me to see exact chrono results). And that’s the most likely cause, or predominant cause of it failing to stabilize the 55grs.