Ar pistol barrel profiles?

[TurboLag]

Anyone know why barrels shorter than 10" are typically what looks like cut down bull barrels? I had a hard time finding a light weight 7.5" barrel that wasn't a big meaty steel rod.

[nate89]

I was looking for a short 300 BLK barrel and noticed the same thing. The CMMG 8" barrel was trimmed down, but almost every other one I saw was a heavy profile. I don't know the reason, but I'm interested in finding out as well.

[HardToHandle]

To maintain stiffness when heated?
I had a 7.5" .223 that was unbelievable. Acting as a heat sink is my thought, associated with location of chamber.

[TurboLag]

To maintain stiffness when heated?
I had a 7.5" .223 that was unbelievable. Acting as a heat sink is my thought, associated with location of chamber.

What was unbelievable about it? That's a good point about heating. But is also small enough once hot it can't droop as much as say a 14.5 since it's small.

[jbjh]

My guess; For 10.5 and longer, they grab a carbine barrel out of the stack and cut it down. Under 10.5", they probably have to contour their own blanks. It might not be worth profiling the rest of the barrel. They just make the whole thing .750 and be done with it. Less machining=more profit.


Sent from 80ms in the future
Much peace
Jimmy

[TurboLag]

Also could be to reduce POI shift with a can. But then not a lot of 7.5" are used with a can unless it's in 300

[TehLlama]

My guess; For 10.5 and longer, they grab a carbine barrel out of the stack and cut it down. Under 10.5", they probably have to contour their own blanks. It might not be worth profiling the rest of the barrel. They just make the whole thing .750 and be done with it. Less machining=more profit.


That's exactly what I was thinking - just put a chamber, muzzle threads, and a gas block journal on the blank and sell it. Side benefit is more thermal soaking capable mass (since historically AR pistols were range toys more than practical items - I'd still argue that in 5.56 anything under 10" is either a tiny niche or novelty item) which means they can be more fun to dump large quantities of cheap ammo through them.
I've seen some more reasonable profiles on a lot of the 300BLK/300WHSP options in the 7-10" range, but that's actually in the range where those projectiles perform out to 100yd at those muzzle velocities - so in BLK (especially with a can) I'd actually look for a smart implementation of a medium/tapered contour setup, or if it's without a can (compact/packable AR Pistol - especially with 20rd or limited # of mags), then I'd go for a lightweight setup.