7.5 vs 10.5 ar pistol

[JBKnifeworks]

The 300 BLK loves short barrels.

 

[Wallace's]

 

[MilSpec308]

With a 7.5" barrel you will never get the round up to the minimum 2500 fps that it needs to tumble and fragment. The bullet will tumble in flight as well on medium to long distance shots because it won't have enough spin to stabilize it past a certain distance. At close distances the round will pass through flesh (over penetrate) because it is moving to slow to fragment and tumble.

So basically the 5.56/.223 round is moving and spinning to slow to be of any use at any distance.

The .30 caliber bullet however functions fine out of a short barrel. The round even though it is moving at a much lower velocity will tumble in flesh at close range and will be stable out past 200 yards.

This! If your intentions are to use a Pistol/SBR type AR for SD, don't go under 10.3" in 5.56/.223. If you do go under 10.3" to use it for SD, I'd look more closely at 300BO, 6.8SPC or 762x39.

 

[zaetiger77]

this! If your intentions are to use a pistol/sbr type ar for sd, don't go under 10.3" in 5.56/.223. If you do go under 10.3" to use it for sd, i'd look more closely at 300bo, 6.8spc or 762x39.

church! !!!

 

[Tech Jacket]

Very true This is what saved a bunch of our asses during the court house shooting a couple of months back. Poorly functioning 7.5" I wont build shorter than 10.5"View attachment 308970

the courthouse shooting was stopped by an AR pistol with a SIG brace used by local LE? Wow. Things channel 5 dont tell ya are on the ODT!

 

[mtdawg169]

A 7.5" barrel will work fine as long as you open the gas port up. It will be a little gassy and you'll need a heavier buffer, but it will run good

Gassy and heavy buffers don't equate to running good in my book. That's just putting a band aid on a problem.

 

[mtdawg169]

the courthouse shooting was stopped by an AR pistol with a SIG brace used by local LE? Wow. Things channel 5 dont tell ya are on the ODT!

God, I hope not. We'd never hear the end of it. It's pretty unlikely since LE can easily get SBRs. I'm sure he was just referring to the 10.5 barrel.

 

[MilSpec308]

Gassy and heavy buffers don't equate to running good in my book. That's just putting a band aid on a problem.

Well a 7.5" barrel unless you're running a piston system will never be adequate. It's poor for SD, lacks down range accuracy and ballistic performance, but is a fun little range toy. 10.5" is optimal and shortest length IMHP you can use and still achieve fragmentation out to around 250-300m and still get roughly 2500+ Fps out of your ammo. I had a 7.5" AR pistol with roughly 5,500 rds through it and never once had a problem. Just wasn't ideal for anything more than a noise maker at the range

 

[mtdawg169]

Another 7.5 pistol thread, must be Tuesday. Seems like the regular rotation on here is:

Monday - I can't find any 22lr!
Tuesday - the 7.5 AR pistol is the ultimate AR!
Wednesday - I hate 22lr flippers!
Thursday - Sig brace rocks! (aka SBRs are stoopid)
Friday - someone is drunk posting
Saturday - Lax comes up with a strange, but oddly intriguing suppressor host
Sunday - I broke my AR, please tell me how to fix it, so I can ignore good advice and bubba gunsmith a half a**ed solution

 

[Wallace's]

Well, I will say it since its not been noted in this yet....

Good luck on a warranty claim for baffle strikes using a 7.5". Not sure how many, if any, can manufacturers warranty under 10"?????