SBR

[Voodoochild]

So if you had to choose between a 12.5 or a 14.5 inch what would you choose and why? I am looking at either a Noveske 12.5 Crusader or a 14.5 Afghan. I know one is a Middy and one is a Carbine gas system. But what are the advantages/disadvantages of each? And what contour would you choose and why?

I currently have a 16" RRA Entry Tac and it is a heavy bugger but has never failed to go boom (except for Wolf ammo). I appreciate the info you all can provide.

[miserai]

im not an expert on SBRs. but they way i think of it is, if your gonna pay a $200 tax then go with something thats worth it. id go with the 12.5". to me an inch and a half isn't worth the tax and paperwork when you could just go with a permanently attached break or flash hider.

thats just my $0.02

[Kyrinn]

Agreed.
The point of an SBR (in my mind) is its compactness.

[Aubrey]

[QUOTE=Voodoochild]So if you had to choose between a 12.5 or a 14.5 inch what would you choose and why? I am looking at either a Noveske 12.5 Crusader or a 14.5 Afghan. I know one is a Middy and one is a Carbine gas system. But what are the advantages/disadvantages of each? And what contour would you choose and why?...QUOTE]

It depends upon your needs which would be the better choice.

Obviously the 12.5" barrel allows for a more compact weapon that is easier to maneuver in close quarters (in structures and vehicles). If ranges are short, then the reduced velocity of the shorter barrel is less of a concern.

If ranges will potentially be longer, the higher muzzle velocity of the longer barrels will improve the terminal ballistics (greater likelihood of fragmentation/expansion of the bullet) while being slightly less "handy."

[Robb Jensen]

So if you had to choose between a 12.5 or a 14.5 inch what would you choose and why? I am looking at either a Noveske 12.5 Crusader or a 14.5 Afghan. I know one is a Middy and one is a Carbine gas system. But what are the advantages/disadvantages of each? And what contour would you choose and why?

I currently have a 16" RRA Entry Tac and it is a heavy bugger but has never failed to go boom (except for Wolf ammo). I appreciate the info you all can provide.

I have two 11.5s and a 10.3", the 10.3" was a factory 14.5" LMT that I had cut down and the gas port opened up.

14.5"
http://img.photobucket.com/albums/v408/gotm4/gunpics/3gunrifle004.jpg

same gun at 10.3"
http://img.photobucket.com/albums/v408/gotm4/gunpics/newpics002.jpg

[padwan]

Given the 2 lengths, and that both are coming from Noveske, I'd go 12.5" in the lightest profile available, unless you're intending to go suppressed in which case, a thick enough profile would be required.

With an SBR, i like to look not just at OverAll Length, but also at Overall Weight. I don't see a light profile Afghan offered as an option, so the vote goes to the 12.5.

Also, the 12.5 Polygonals seem to push the bullets at 14.5" velocities so that's a good thing. I assume you're looking at mounting an optic as well. The lighter package gives you some options while allowing you to stay at a reasonable weight range.

FWIW, I do have a light profile Crusader with a vortex on the end and a S&B Short Dot on a Larue SPR-E mount, and the package is quite manageable while still being accurate. Black Hills 75 is what I usually run on this set-up.

[Voodoochild]

Upon further review I am going to go with a Noveske 10.5" with a DD 10" lite rail and maybe a VLTOR or Noveske Gas Block. Kind of like what Stick has posted on TOS if you haven't seen it look for it. Very nice setup.

[WILDBILL]

Hi, I plan on going with the LMT 10.5 Upper to go with one of my two -LMT Lowers. You said if you go then go real compact. I want to build a NAVY LMT MK18 MOD0 clone.

[rsilvers]

Also, the 12.5 Polygonals seem to push the bullets at 14.5" velocities so that's a good thing.

I would like to see a test on this. Arms Tech made a similar claim and it was false though it got printed in a magazine took in a lot of people who did not do their own testing as proof and the company seemed to do all they could to prolong the misinformation. Most likely as it was a boom for sales. I not think Noveske even makes such a claim.

I would go with the 12.5 unless you are building an M4 clone complete with stepped barrel. 14.5 is neither here nor there. I wish the military went with 16 or 18.

[tikkafan]

There were a lot of claims about polygonal rifling that came along with the XM8 trials. I have access to a chronograph, so guys just send me the barrels and I'll do some testing. :D

[ashooter]

I would like to see a test on this. Arms Tech made a similar claim and it was false though it got printed in a magazine took in a lot of people who did not do their own testing as proof and the company seemed to do all they could to prolong the misinformation. Most likely as it was a boom for sales. I not think Noveske even makes such a claim...

I have seen chrono data from several people I trust and all of Noveske's barrels seem to give roughly the equivalent velocity as 1.5-2 inch longer chrome-lined barrels. There are several threads over at 10-8 with chrono data for 10.5" to 18" barrels.

My guess is his tighter throat has more to do with it than the polygonal rifling itself, but the polygonal rifling seems to help with barrel longevity.

[rsilvers]

I agree. The barrels would have to be cut with the same chamber reamer to make the tests meaningful as just going from a .223 to 5.56mm chamber alters velocity a bunch.