Barrel twist question

[torowy]

Hello all,

This is my first post, I have read on here a little and you guys seem to know what you are talking about. I am building and AR, leaning toward a .204 ruger. I have a question about barrels and twist rates.

From what I understand, most factory barrels on a 204 are a 1:12 twist. I have read that that is right on the cusp for a 40 grain bullet. That some guns shoot a 40 grain in a 12 fine, and some tumble. Most factory 204 ammo ranges from 30-40 grains. Some of the really long range shooters are using 55 grains. I think the 55 grain bullet shooters are using a 1:8 or a 1:9 twist.

Have any of you experienced negative effects from shooting to fast of a twist barrel on lighter bullets.

Ideally I would want a barrel that I could shoot 30-55 grain bullets in and have it shoot them all well. Is this a real possibility?

Will an 11 or 10 get a 55 grain bullet to stabilize and not rip a 30 grain bullet to shreds?

I think 90% of my shooting will be with bullets in the 30-40 grain range, but I want the capability to shoot a bigger bullet (55 grain or so) maybe at some longer ranges.

So really, I am looking for a twist that will shoot all of these bullets well. Something fast enough to stabilize a 55 grain bullet, but still shoot the 30's without any problems.

What have you expereinced?

thanks,

[MT204]

Greetings
I had many of the same questions that you had.
Here is my solution.

http://www.204ruger.com/forum/viewtopic.php?f=2&t=6972

So far have shot up to 40 grain with great success. I would have gone with 11 twist but Shilen only did 1:10 for the type of barrel I wanted.

[torowy]

so you got a 1:10? have you shot 32 grain bullets? How are your groups?

[Wrangler John]

Here is a web site that'll help: www.jbmballistics.com/cgi-bin/jbmstab-5.0.cgi

Plug in the numbers and you'll see how stable a bullet is at any given twist, velocity, temperature, or atmospheric pressure. I've been working with the lead free bullets that require a faster twist, and find this calculator helpful. One ballistic expert I read said the idea of over stabilization from fast twists was an old wives tale. May be true, but I found that too slow a twist results in very poor performance, to the point of bullets tumbling sideways through targets, or missing the entire target frame.

[torowy]

I tried that calculator, the faster twist you do, it says that it makes it more stable.

However, there are other forces affecting those bullets. If you spin a bullet too fast it can dissinigrate.

[jo191145]

Excessive twist for bullet length/weight will exacerbate any defects in the core balance. Bigger groups and disintegration. Some bullets just can't handle the extra RPM's period.
I've shot some 55gn Noslers out of my 8 twist 6BR for foulers. All made it to 200yds and the group was'nt half bad. Considering it was just an arbitrary powder charge and seating depth that is

I still like to have a little more twist than not enough tho. I have a 14 twist 6BR that just does'nt seem to like the 68gn fare as much as it should. Drop down to 58gn V-Max and it bugholes nicely. My 14 twist 6ppc seems to have no problems puttin 68's in one hole. Lots of folks going to 13.5 twist these days.

towry

I have no expierience with a lot of uberfast twist 204R barrels or AR's.
Still I think your asking to much from one tube,one twist.
First the 55gn Berg is considered just a little heavy for the 204 case. Sure you can shoot them but at what velocity. Is it worth it?
Secondly can you hot them up enough in an AR to make it worthwhile? Will the gas system operate with slow powders?
Just some questions to add to your own

On the other side of the coin theres this. If you have a faster twist tube that will shoot the 39 bk or 40's theres no reason to shoot the 32's.
The 39bk will give you the splat performace of a 32 with much greater BC to boot.

[stevecrea]

Torowy:

Your question is an excellent one, and one I have wondered about.

I recall that one of the AR makers, perhaps Stag, specifically notes on its website that for the .204 with its standard 1 in 12 twist, bullets over 36 grains should not be expected to work well. I do not know if the weight of the bullet has anything to do with the operation of action in an AR, but other than that, this would appear to be an explicit statement about what many people have noted on this site: the 1 in 12 twist is not satisfactory for the heavier bullets as far as accuracy and stabilization.

However, that does not answer your question, which was about the possible drawbacks of a faster twist. I seem to recall reading information somewhere that suggested that you should use the slowest twist possible for the bullets that you expect to use, for the primary reason that you cite: possible disintegration of the bullet. But also, you are probably risking your rifle to more than necessary wear in the throat by selecting a too fast twist. Also, I would suspect that a too fast twist may result in more copper fouling in the barrel, other things being equal.

Your range of 30 to 55 grains is pretty broad, as I am sure you know. Which end of that range is more important to you, and at which end of that range would you expect to shoot the most?

[giterdone]

Torowy.....If 90% of your shooting will be using 30-40gr. bullets, it makes more sense to go with the standard twist and use something in .224 caliber for the 50-55gr. bullets like another upper for your AR ?

[Wrangler John]

Don't worry about spinning the average crop of bullets too fast in reasonable twists. The one sure disintegrating bullet I came across was the old .224 45 grain Hornet bullets driven out of .22-250 at just a tad over 4,000 fps. This was a 1:12" twist Hart barrel. That bullet was a true blue streak vapor trailer - it didn't make it to 150 yards, but left a neat visible smoke line right to the squirrels. It also hammered them within 100 yards. The other was a 60 grain .257 bullet made for the .25-20 etc. that one out of a .257 Roberts Ackley also vapor trailed, but shot under an inch at 100 yards. Velocity and jacket construction has as much to do with it, maybe more, than twist rate. I recall the old Hornady .224 50 grain SX bullets were labeled not to exceed 3,500 fps, or was it the Sierra Blitz?

Just came back from breaking in a .243 WSSM Brux cut-rifled barrel with a 1:8" twist for the 62 grain Barnes Varmint Grenade. These bullets did not stabilize in a 1:14" twist 6mm PPC, and were barely stable in a 1:10" twist Shilen Select Match barrel. Early results show a fantastic improvement with the faster twist, three shot groups running just above caliber diameter. The Miller calculator showed the 1:14" PPC twist producing a stability factor of 0.600, or unstable at 3000 fps. The 1:10" twist produced a stability factor of 1.180 or under the 1.50 minimum at 3000 fps. The 1:8" twist produced a S.F. of 1.942 or well into the stable area with the WSSM at 3,500 fps (minimum velocity for this cartridge and powder combination). Target results mirrored the Miller Calculator predictions. These are extremely frangible powdered metal core bullets, yet showed no signs of in-flight disintegration. Same with the Barnes 36 grain Varmint Grenade in a 1:10" twist .22-250 at 3570 fps, or the Barnes 36 grain V.G. and Nosler 35 grain Lead Free BT at 3,200 fps in a 1:9" twist polygonal barreled .223 Remington. Overall, my results show that a higher than average stability factor is not going to negatively effect accuracy or bullet performance. One additional step up in twist rate is not a bad idea. Which is what the 1:11" twist is for the .204 Ruger.

My .204 Ruger 1:12" twist Shilen barrel shoots incredible .247" 10 shot groups with the 26 grain Varmint Grenade, demonstrating that each bullet is a separate critter. Weight to length and ogive shape are the greatest influence on stability. If any of the commercial bullets are not stabilizing in the "standard" 1:12" twist, then going to a 1-11" or 1-10" or using the Miller Calculator to test what is stable should avoid any problems.

I am anxious to see what those .243 Varmint Grenades at 3,800 fps do to squirrels - probably be enough to gag a gross anatomy class.

[Ray P]

I have a question on barrel twist tolerance? I have 3 Ruger 204's 2-custom with Hart barrels 1 in 12 by 26.5 and a factory Ruger No.1 1 in 12 in varmit contour 26". All shoot 40 grn v-Max, 40 Bergers abd 39 sierra's into groups in the .1's to .3's if I do my part. When I ordered my Hart barrels. Hart only made 20 cal in a 12 twist. Today Hart makes 9, 10 & 12 twist in 20 cal. Just wondering how close in twist tolerance the barrels are realy held? Plus or minus 1/16, 1/8, 1/4 of a certine twist.
The last few posts here about barrel twist on the Ruger 204 are say that some 12 twist are marginal for 40 grains tips? I belive this was the starting twist when this lil caliber was born. Factory barrel twist tolerances going by the way side?
Thanks to all that reply and Merry Christmas to all!!
Ray P

[WaltherP99]

The last few posts here about barrel twist on the Ruger 204 are say that some 12 twist are marginal for 40 grains tips? I belive this was the starting twist when this lil caliber was born. Factory barrel twist tolerances going by the way side?
Thanks to all that reply and Merry Christmas to all!!
Ray P

It was the starting twist and they were using the 32 grain bullets as the prime.

[Ray P]

WaltherP99.......Thanks for the reply. Your are 100% on. I had forgot that starting load was with a 32grn and not the 40. Still some of the 1st rifles out handled the 40 v-max ans 39 sierra's with no problem. The problem has surfaced in last few years. That why I had a question on twist tolerance? We all strive to load the the best handloads possible. Weighing cases, checking powder charges, using the best powder possible.
Later
Ray P

[Bayou City Boy]

For years prior to the 204 Ruger, 20 caliber shooters were using 13" twist barrels and they worked well with the available factory bullets which were a 36 grain Berger Hp and a 33 Grain (yes....33 grain) Hornady V-Max. Moving closer to the time the 204 Ruger was introduced, 12" twist barrels became more common as predator hunters were looking for heavier - and hence typically longer - bullets for predators the size of coyotes. The longer, heavier bullets came from custom bullet makers who were few and far between.

When Ruger and Hornady announced their new rifle/ammo combination, the rifles were introduced with 12" twist barrels. To help achieve the advertised velocity of the 204 Ruger when it was first introduced, Hornady dropped the weight of their light bullet by one grain - to 32 grains and introduced a 40 grain bullet. Berger dropped the 36 grain bullet and introduced a new line of 20 caliber bullets including the 35 and 40 grain HP bullets that seem to be among the more reliable coyote killing bullets today.

As I've mentioned before, I hand swage my own 20 caliber bullets and for predators I prefer a 38 grain HP bullet that is short enough to shoot through any 12" twist barrel.

To answer the question above; Bullet length is the dominant deciding factor as to which barrel twist rate will work for any bullet. Heavier just tends to follow longer (except for VLD bullets) and bullet weight is an easier way for bullet makers to specify which bullets will or will not shoot in a barrel of a designated twist.

When the early 204 Ruger rifles were on dealer shelves and no factory Hornady ammo existed, I was finally able to get my hands on Hornady 40 grain ammo before I found any 32 grain. Before that, I had obtained as set of 204 Ruger dies and I made 204 Ruger brass from 222 Rem Mag brass. The combination of 222 Rem mag brass and my 38 grain HP bullets had me shooting my new Ruger rifle long before ammo was available. That brass is still some of the best 204 Ruger brass I've shot.

-BCB