7.62 semi-auto 1:10 versus 1:11.25

[captnmo]

For a 20" semi-automatic rifle, what is a preferred twist rate for precision shooting? The M110 went with the 1:11, M14/M1As are 1:11.25, GAP does the 1:11, LWRC REPR gives you the option for either 1:11.25 or 1:10 and Noveske does 1:10.

My concern is if I go with a 1:11.25 will I not get the accuracy out of the heavier rounds like 175 SMKs that I could with a 1:10. But if I get the 1:10, will I not be able to shoot 150-155ish for plinking and hunting worth a damn. Of course, that last question would mean that "over twist" on a lighter round is possible from a 1:10.

 

[ggmanning]

Re: 7.62 semi-auto 1:10 versus 1:11.25

My POF is 1:10 and shoots 155 and 175 very well.

 

[phxfa]

Re: 7.62 semi-auto 1:10 versus 1:11.25

My MWS doesnt shoot 150's for shit and its a 1:10 and it likes 168's-175"s,,My OBR shoots everything good and its 1:11.25 YMMV

 

[ORD]

Re: 7.62 semi-auto 1:10 versus 1:11.25

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ggmanning</div><div class="ubbcode-body">My POF is 1:10 and shoots 155 and 175 very well. </div></div>

^^ This has been my experience too. ^^

Great shooting with both 155gr Lapua Scenars through 168gr and 175gr SMKs from my POF P-308.

 

[okiefired]

Re: 7.62 semi-auto 1:10 versus 1:11.25

Remember, its not the weight of the bullet that matters, but the length. In my experience, the Palma type 155's (Scenar's, Amax, SMK, etc.) with a long ogive prefer the faster twist barrels just like the 175's and 178's do. My 11.25 twist AR10T shoots both very well, most say the 10 twist does too. Most of the 150's are a different animal, shorter ogive, and I would assume would do better in a slower twist, maybe a 12. I dont think there is much of a selection of match grade 150's though.

okie

 

[Hutchman20]

Re: 7.62 semi-auto 1:10 versus 1:11.25

i have an lwrc repr with the 11.25 and it shoots 168s great.

 

[BCP]

Re: 7.62 semi-auto 1:10 versus 1:11.25

I was told 180 is max for 1:12, 200 for 1:11 and 220+ for 1:10. As far as what bullet it likes that will be trial/error and depends on lots of different factors.

FWIW my 308 is 1:10 and shoots 150-190 fine.

 

[M21guy]

Re: 7.62 semi-auto 1:10 versus 1:11.25

No two are identical. A better barrel is probably more beneficial than slight change in twist rate. My Krieger with a 1/10 twist shoots 150's well. As good as 168's. Shoots 175's very well. I replaced the 1/11 twist barrel with the faster twist. Still shoot the same range of ammo I did before, but better.

 

[captnmo]

Re: 7.62 semi-auto 1:10 versus 1:11.25

Good info! Reason I'm asking is I'm thinking of selling my current AR-10 and taking the plunge into a LWRC REPR 20" and they offer the selection between the two twists. I don't want to compromise the accuracy this rifle will give me by going with a slower twist for the sake of shooting plinking ammo. I primarily want accuracy but able to put something like 155 Scenar through it with the same quality of accuracy as I would with a 175 SMK.

 

[Anchor Zero Six]

Re: 7.62 semi-auto 1:10 versus 1:11.25

Have you factored in that all of the 1:11 you mentioned are 5R?

Seems most makers will defer to expressing the twist as 1:11 vice 1:11 point whatever (rounding down).

5R will give you some added FPS down the tube and they resist fouling which also helps velocity.

So to answer your question I say go for the 5R but more so because of the 5R attributes and not the twist rate itself. For heavy LR projectiles 1:10 1:11 and 1:12 will all do you right.

 

[okiefired]

Re: 7.62 semi-auto 1:10 versus 1:11.25

Once again, weight is not as much a factor, its the length of the bullet that counts. As a "GENERAL RULE", longer profile bullets perform better in a faster twist barrel. Hav'nt used many but I have yet to see a 150 do very well (comparitively speaking) in a 10 twist...or 11.25 for that matter. On the other hand, the long 155's do very well in the faster twist. IMHO, between the 11 and the 10, barrel quality will make more difference than twist with the bullets you're speaking of. I cant find any use for 168's.

okie

okie

 

[captnmo]

Re: 7.62 semi-auto 1:10 versus 1:11.25

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Anchor Zero Six</div><div class="ubbcode-body">Have you factored in that all of the 1:11 you mentioned are 5R?</div></div>

No, I didn't know that. I'm just learning about the 5R and it's advantages. So the LWRC REPR 1:11 is 5R?

 

[Anchor Zero Six]

Re: 7.62 semi-auto 1:10 versus 1:11.25

No expert not claiming to be, honestly never looked into LWRC but LMT SS barrels and the POF are positivly 5R.

There are other variations on 5R since I think thats some sort of trademark. Polygonal is another term you may see.

Not sure if its a stead fast rule across the board or not but conventional rifling is 6 groves (even number 1:10, 1:12 etc) 5R is 5 groves (odd number 1:11) not sure if the two are directly linked but thats how I look at it.

Stop over thinking it LOL just get the the 1:11 and call it good, reason why all of the ones you asked about are using it...it works

 

[MK14 SEI]

Re: 7.62 semi-auto 1:10 versus 1:11.25



It's my understanding that .308/7.62x51 performs best with a 1:10 ROT when a sound suppressor is used.

I use a sound suppressor and all of my M14s have a 1:10 ROT.
I shoot 147 gr NATO surplus, 180 grain "sub-sonic" and everything in between.

Hope that helps.

 

[captnmo]

Re: 7.62 semi-auto 1:10 versus 1:11.25

Got an email back from LWRC and they say all their rifles use polygonal rifling. Not sure if it's 6 groove or not but it sounds like a good setup.

 

[Lowlight]

Re: 7.62 semi-auto 1:10 versus 1:11.25

Instead of worrying about 1/0 vs 1/11 you might want to consider the fact the LWRC REPR has a least than stellar reputation for accuracy. So do you really thing you'll see a difference with a gun that shoots over an MOA

 

[BCP]

Re: 7.62 semi-auto 1:10 versus 1:11.25

When the repr came out a buddy of mine blew 4k-4200? on a 16" model. It shoots MOA with match ammo. My 1635$ DPMS mixmaster shoots tighter groups than that. If group size is your thing the lwrc wallet raper is not the rifle for you. Have a rifle built for you instead.

 

[captnmo]

Re: 7.62 semi-auto 1:10 versus 1:11.25

Hmmm, that's a perspective I've not heard. I heard nothing but good things but I can't honestly verify the sources. After reading a few reviews of other Hide members, it seems averaging around .75 to 1 MOA.

BTW, I am also considering a GAP POF AR-10

 

[ORD]

Re: 7.62 semi-auto 1:10 versus 1:11.25

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: captnmo</div><div class="ubbcode-body">BTW, I am also considering a GAP POF AR-10 </div></div>

Well between the REPR and the new GAP-10...its an absolute no-brainer! GET THE GAP FOR CRYING OUT LOUD!!!!

 

[captnmo]

Re: 7.62 semi-auto 1:10 versus 1:11.25

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ORD</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: captnmo</div><div class="ubbcode-body">BTW, I am also considering a GAP POF AR-10 </div></div>

Well between the REPR and the new GAP-10...its an absolute no-brainer! GET THE GAP FOR CRYING OUT LOUD!!!! </div></div>

Well damn! Guess I ought to start making some phone calls to GAP LOL

 

[Lowlight]

Re: 7.62 semi-auto 1:10 versus 1:11.25

When someone pays a fair amount of cash for something of course they are going to say it is great... many feel these decisions are a direct reflection on them as a person.

Not to mention you never see "all" these Sub MOA Semi Auto Shooters in person... Shooting a semi auto 308 is not the same as a 5.56 or a boltgun, to do it consistently takes effort, understanding and training, it's not a simple matter of pulling the trigger and letting it fly. Granted even a blind squirrel finds a nut every once and while, the majority just don't shoot them very well.

When you have no vested interested it, you tend to call them as you see them. 1 MOA today is nothing to write home about, the POFs will hover around 1/2" the OBR, GAP, all come in under that... if you are shooting 1 MOA chances are it is really 1.5" on a consistent basis.

 

[Howie Feltersnatch]

Re: 7.62 semi-auto 1:10 versus 1:11.25

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">...the lwrc wallet raper...</div></div>

Haha I like that!

 

[captnmo]

Re: 7.62 semi-auto 1:10 versus 1:11.25

Well, to add to this discussion, the whole thing came about when the opportunity arised to maybe purchase a REPR for about the same as a new GAP with a few upgrades would cost me. I've been considering upgrading to a piston 308 and I like the other features of the REPR such as the trigger and side charging handle. Hence the questions regarding twist rate.

Otherwise, at the current market price, I wouldn't even consider it. So please don't construe what I just said to mean I'm dead set on it. But it's worth strong consideration since it has a lot of features I've been wanting but was out of my price range until now. Otherwise, the other option would be a 20" POF since I'm going for a piston upgrade. The other "goodies" on the LWRC are nice though.

So if the price I'm thinking I can get it at is possible, would that change any of your thoughts on it?