Rifling twist rate

[Hunt]

What twist rate is needed for the heavier 22LR bullets? There is a 60gr and I think I may have seen an 80gr.

[subscriber]

Who makes the ammo? Don't they have a recommendation? Aguila just suggest "faster twist" and 20" long barrels for their 60 grain bullets: https://www.aguilaammo.com/products/...ad-solid-point

I think we know that 1:16 is too slow for 60 grain .22 LR bullets, as many experience tumbling or keyholing with standard barrels. The longer sharper 62 grain 5.56 bullets require 1:9 twist, so 60 grain round nose subsonics are not going to need that fast a twist, but should work with it.

Everyone know 22 Plinkster: https://www.youtube.com/@22plinkster/videos
He may be able to answer that question with real experience: 22plinkster@gmail.com


1:14 ; 1:12 and 1:9 .22 LR barrels exist. It sounds like for 40 grain bullets 1:16 is as good as 1:14. Faster is not better with standard bullets:
https://www.youtube.com/watch?v=uqDp5zBObQ8


I vaguely remember 1:14 twist being good for 60 grain .22 LR, but can't remember the source.

These long copper 50 grain bullets seems to require 1:7 twist barrels. That seems fast. Perhaps because of their long nose and more tail heavy profile: https://cuttingedgebullets.com/curx-...r-bundle-200ct

[Hunt]

Considering the velocity of 223 I didn’t use it for any kind of reference in my thinking. Looks like most the low velocity 22LR is in the 40-45gr weight, doesn’t make sense to me, 90lb ME for the 40gr and 120lb for the 60 gr. Must be a good reason for that. I am thinking the popularity of twist rates.

[FeuerFrei]

I tuned one of my 1022's to run subsonic 60's and accuracy with a 1/9 green mountain barrel is good. 38 gr subsonics also are accurate. Getting that thing to cycle was a pain in the balls tho.

HV 22 will scatter my groups thru that rifle.

The comment about longer barrel 1/16 is mostly true in my testing of 60's. It depends on the rifle and the barrel's bore condition. I don't care to split hairs at that point. Too many variables to chase after.

[subscriber]

Required bullet spin for stability is highest around the speed of sound. Barrel twist requirements are lower, if the muzzle velocity is sub-sonic; or well over the speed of sound.

Proper twist calculators show twist requirements as a function of bullet velocity. Here is an example where you can plug in your numbers: http://www.geoffrey-kolbe.com/barrel_twist.htm .
Below is a sample chart generated by the calculator (not for the 60 grain .22; but as close a sample graph as I could find).

As longer barrels achieve the max muzzle velocity and thus spin velocity from a given twist barrel. Provided that the bullet starts off sub-sonic, its stability increases as its velocity drops over range - because spin decays more gradually than forward velocity.

A .223 with 55 grain bullet can reach around 660 yards before its velocity has decayed to 1200 FPS. Beyond that point it becomes trans-sonic and does not spin fast enough to remain stable; then ultimately tumbles. So, to shoot a 55 grain spitzer boat tail .22 bullet at 1200 FPS muzzle velocity will require a faster than 1:7 barrel twist. But then it starts out much faster than that from a typical rifle barrel.

[Hunt]

Good info thanks for the response

[kendog4570]

Looked into this several years ago when the heavy 22's first came out. The stuff is a little better than bulk grade ammo at best. Save yourself some aggravation and $$ and get a high quality target gun with a 16" twist and use high quality target ammo. You'll hit what you aim at with surprising consistency.

[FeuerFrei]

Originally Posted by kendog4570

Looked into this several years ago when the heavy 22's first came out. The stuff is a little better than bulk grade ammo at best. Save yourself some aggravation and $$ and get a high quality target gun with a 16" twist and use high quality target ammo. You'll hit what you aim at with surprising consistency.

Not my experience at all with the heavies. It'll cull g squirrels at 100 yds and pinch'em in the head with boring consistency. I put it together for pranging freeloading varmints on my ranch.

*they do have a ballistic arc like a rainbow tho and do not perform as well in an AR clone w/1/9 16" barrel. 22 kit, not dedicated upper.
*bullet hang time to target is noticeable. Sloooow.
*it is a niche type ammo. do the homework and have realistic expectations.
*subsonics are bread n butter in the same rifle with similar accuracy results. YMMV

Great project to work on. Lots of r&d, t&e time needed to do from scratch.

[kendog4570]

I guess I am coming from the angle that I already had the guns and ammo and nothing to be gained over what I had. No sense gearing up for performance I was already getting. Almost 200 yard kills on ground squirtles (19 MOA up!) with Anschutz 64 MS with old (good) lot of SK Std Plus. The bullets were more falling on them than hitting them horizontally.
Either way, sounds like we are both having fun.