1:10 Vs. 1:12 twist .308 Pros and cons

[dustiningram07]

I am new to precision shooting and really only know the m4, mk48, 240, and other weapons issued in the army.
I am looking at a remington 700 sps as a starter rifle, i want to suppress it like i did with my walther p22 and ruger 10/22 but i read about 1:10 twist being better for a suppressor...why?

what are the pro's and con's of the two rifling twists and why is that important to you, as a shoooter?

 

[WesP]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

1:10 is capable of stabilizing a subsonic round better than a 12 twist and the last thing you want with a suppressor is bullet instability

 

[jagged77]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

You would certainly need a 1:10 twist if you were to shoot subsonic rounds out of a 308. Thats a bit of a specialist application however.

If you are just using the sound moderator to cut down the db level and recoil on normal loads, a 1:12 should shoot up to 175gr. I run 168 SMK's out of my 700 1:12 just fine.

 

[Anchor Zero Six]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

Split the difference and get a 700 5R Milspec with 1 in 11.2" twist. The 5R will produce similar if not better velocity tas a 1 in 10.

As mentioned already the rational is to stabilize the heavy rounds which are what you would be using in a Sub Sonic load.

As you dive deeper into this forum you will see that the 5R is the #1 reccomended rig for entry level shooters. Its a well configured rifle out the box and you can upgrade as you go if you desire to change out the stock or anything else.

BTW welcome to the Hide.

 

[longebow]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

True subsonic rounds for the .308 may actually require a twist rate as fast 1/9--again, as Jaggedd77, a very specialist indication/application. 1/10 will stabilize .308 bullets from 125 to 200 grains. If you plan on shooting up to 190 grain Sierra MatchKing bullets, 1/12 will usually do it. 1/11 is a nice compromise.

 

[bm11]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

From my limited knowledge, the benefit to a faster twist rate is the ability to stabilize heavier rounds. The cost is reduced barrel life.

 

[rsilvers]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longebow</div><div class="ubbcode-body">True subsonic rounds for the .308 may actually require a twist rate as fast 1/9--again, as Jaggedd77, a very specialist indication/application. 1/10 will stabilize .308 bullets from 125 to 200 grains. If you plan on shooting up to 190 grain Sierra MatchKing bullets, 1/12 will usually do it. 1/11 is a nice compromise. </div></div>

Actually 1:8 for subsonic 220 MKs. Sometimes 1:7 for 240 MK. 1:10 is for supersonic 175s and up and some limited subsonic use with shorter bullets.

 

[wnroscoe]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

The SPS will be 1-12 and 168/175's will work very well suppressed or not.

If you work the Greenhill Formula for the 168/175 SMKs it says that 1-11.76 twist for 168's and 1-11.55 twist for the 175's

All of my 1-12 twist 308's shot each bullet very well but the 175's had the edge.

 

[AlabamaShooter]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

I shoot a 1-12 twist barrel in my .308, it shoots the 168gr bullets just fine, but the 175's are just a hair better in my rifle.

 

[longebow]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rsilvers</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longebow</div><div class="ubbcode-body">True subsonic rounds for the .308 may actually require a twist rate as fast 1/9--again, as Jaggedd77, a very specialist indication/application. 1/10 will stabilize .308 bullets from 125 to 200 grains. If you plan on shooting up to 190 grain Sierra MatchKing bullets, 1/12 will usually do it. 1/11 is a nice compromise. </div></div>

Actually 1:8 for subsonic 220 MKs. Sometimes 1:7 for 240 MK. 1:10 is for supersonic 175s and up and some limited subsonic use with shorter bullets. </div></div>

Cool! Thanks Mr. Silvers for the input, and update.

 

[dustiningram07]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

Thanks for all the replies!
I live in Georgia and am looking to sell my 8mm mauser 24/47 and
buy a 700 or savage, anyone in the area please pm me if you'd like to help with either one!

Im looking at reloading equipment but even with jump pay army paychecks suck!

 

[rsilvers]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body">If you work the Greenhill Formula </div></div>

Greenhill is obsolete. Use the Don Miller formula or PRODAS.

 

[wnroscoe]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rsilvers</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body">If you work the Greenhill Formula </div></div>

Greenhill is obsolete. Use the Don Miller formula or PRODAS. </div></div>

Do you have a link to it.....................I know you do

 

[rsilvers]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

http://accurateshooter.wordpress.com/2008/06/03/calculating-bullet-rpm-spin-rates-and-stability/

Use the temp for the coldest you might ever use. So if it is for competition shooting, then maybe 40 degrees F. But if you are selecting twist for a military application, then no more than 0 degrees F.

If you might use a sound suppressor, then look for higher stability factors to avoid baffle strikes. Perhaps 1.5 or greater at 0 degrees F. Without a silencer I would look for at least 1.2 or 1.3 or higher at 0 degrees F.

 

[30cal user]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

I use this:

 

[rsilvers]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

That chart blows. First, it does not consider velocity and seems to assume very long barrels (26 - 30 inch). Second, it says use 1:9 twist for 68, 19, and 75 grain .223. 1:9 is not an acceptable choice for typical bullets in those weights. Then it says 1:10 for 220 grain .30 - perhaps with 300 WM and longer barrels but not for 308 with shorter barrels. Then it says 1:9 for a .260 rifle with 140 grain bullets. 1:8 is more appropriate. Even people who like to avoid fast twist would use 8.5. 1:9 is more for the bullets in the 120 range. In 338 they are suggest 10 twist for a 300 grain. 9 or 9.5 seems to be where things are going for that.

 

[wnroscoe]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rsilvers</div><div class="ubbcode-body">That chart blows</div></div>

I know the number of degrees you have and the level your able to take research to, thats why I'm ROFLMAO.

 

[WesP]

Re: 1:10 Vs. 1:12 twist .308 Pros and cons

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rsilvers</div><div class="ubbcode-body">That chart blows</div></div>

I know the number of degrees you have and the level your able to take research to, thats why I'm ROFLMAO. </div></div>

That might be the most emotion Ive ever seen him try to express.