7.5 or 10.5 inch?

so i plan on building an SBR within a year or two, but can't decide on what length barrel i should go with.
my question is, 7.5 or 10.5? i would really prefer the shorter barrel, but i want to keep rock solid reliability. how reliable is the pistol length gas system on 7.5s? i would much rather have a 10.5 that cycles reliably than a 7.5 that does not. help me out guys!

10.3 is the shortest I would go using 5.56.
I have two 10.5s that have run flawlessly.
My friends with 7.5s have told me that there are some reliability issues with 7.5s but personally I don't know.

I do plan on building a couple of 300blk PDW uppers though.

I started with a 7.5. it has been absolutely 100% reliable.

it is a blast to shoot, and the fireball is quite impressive, its loud as hell too.

I have a 10.3" on the way to me now, so I should be able to do a comparison soon.

if you do end up with a 7.5", make sure you get a 1/7 twist, mine is 1/9 which pretty much precludes me from accurately using the super heavy bullets that are designed to fragment in the shorter barrels at the lower velocity.

thats part of the reason I am getting the 10.3"(velocity and twist rate), plus the longer barrel length will allow me to use my can on it.

I agree I have heard not to go shorter than 10 inches with the 5.56 to maintain half way decent ballistics, also I have heard if you plan on running a can with it the 7.5 beat them up pretty bad, I know any short barrel puts more wear on them but my understanding is the shorter you go the harder it is on them. I do know right on Gemtechs website they say if you put their can on any shorter than 10.3 it voids the warranty.

10.5

Some suppressor MFGs warranty their 30cals below 10" although it would take some research to find out which do.

I recall seeing AAC state the SDN6 was used on a 6.5" 300BLK. I don't know if it was super or subsonic, or what weight bullet/twist rate was used.

Whether or not they'll warranty it if the barrel isn't either a Noveske or AAC if there's a baffle strike is something I'm not sure about if it isn't threaded properly.

There are a great many barrel makers doing 300 barrels now, and some I've inquired about haven't been able to tell me if the threads are concentric to the bore.

I'd only buy from them if I was building a dedicated suppressed 300 and I knew I'd be sending the barrel to ADCO or someone else capable of threading concentric to the bore.

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For fun 7.5 is fine, for anything serious 10.5 is as low as I would go with 5.56. That being said my 300 blackout has an 8" Noveske barrel, but for that caliber it seems fine.

dupe.

My 7.5 inch runs 100%...it's never choked on Wolf, Tula or surplus, either as a pistol or now as a SBR.


It's a blaster, fun to shoot out to 75 or so yards.

Get both!

^^ what he said

Nice..I went with the 7.5 and 12.5 inch SBR set.

I vote 10.5 both of mine are flawless except my psa doesn't like to eject wolf now and then. But for 7.5 the noveske diplomats would get my vote. They got a few videos running it with beta c's.

This will happen...regardless of which length upper you purchase/build first...it's a disease. I recently sold my 7" CMMG piston upper here on the EE. It was 100% but I've gone to a PWS 10.5 pison upper for all around use in 5.56. The 7" uppers are an very small package in 5.56 and mine shot under 2MOA at 100m with the right optics. Great room/house clearing tool...ear protection required while training

That short stick just looks bad-azz!!!

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