Anyone with an AR15 pistol 7"

[dwb1987]

Would it be optimal? No. When you go that short you run into reliability/durability concerns, and give up a lot of ballistics. 10.5 is the minimum Id suggest for 5.56 for serious purposes. And at 7.5" barrel you might as well just use FMJ.

That said I do have a 7.5 upper I built out of spare parts and put the most obnoxious muzzle brake I could find on it, the fireball and concussion is insane. I bring it out now and then for kicks but thats it.

 

[Ammo Jon]

 

[smokey]

This is old, but it gets the internal ballistics across pretty well. 5.56 really shines out of a 20" barrel, does pretty good out of a 16" and probably shouldn't be put through something shorter than around 11" for defensive use.

In contrast, 300blk thumps pretty hard from a 16", is nearly ideal out of a 10.5", and still has decent defensive capability out of a 6".

5.56 will have a lot of flash and rapport out of a <14.5" barrel. 300blk will have less in those shorter barrels due to the nature of the cartridge. 300blk is way more efficient at shorter lengths.

So if it were me, I'd go with a 300blk in something 8-11", depending on the manufacturer. If I really wanted a 5.56, I'd go 11.5". If you aren't suppressing it, you may also want to opt for a badass flash suppressor instead of a comp..

 

[Squaregrouper]

The pistol brace scared me the most.
He should have done another 20-30rds so we could see his can explode.

 

[smokey]

If you're looking for a hard thumper that's also short... there is another option you could look at...

https://palmettostatearmory.com/psa-12-carbine-length-6-5-grendel-1-8-stainless-steel-12-slanted-m-lok-upper-with-bcg-ch.html

Here's my favorite load out of a 12" upper.


It's as good as you get for terminal ballistics out of a 12" or shorter barrel.

 

[Squaregrouper]

If you're looking for a hard thumper that's also short... there is another option you could look at...

https://palmettostatearmory.com/psa-12-carbine-length-6-5-grendel-1-8-stainless-steel-12-slanted-m-lok-upper-with-bcg-ch.html

Here's my favorite load out of a 12" upper.


It's as good as you get for terminal ballistics out of a 12" or shorter barrel.

Good call. I look forward to seeing it in the classifieds.

 

[alucard0822]

In 5.56, mk262 and a couple other heavy loads are the state of the art, primarily because of performance in short barrels. Most data is from 10.5", so there would likely be a little less expansion/fragmentation, more yawing, and probably similar or better penetration from a 7.5". I would definitely recommend a linear comp or flash can, but having fired some out of my 10.5" in 5.56 the 77gr mk262 has a MUCH milder blast than any 55-62gr load, and suppresses a lot better. The black hills 262 mod1 I have tried was also extremely accurate, only real downside is the cost.

Obviously there is a tradeoff of barrel length vs velocity, but what do you get for that tradeoff? pictured is a 16", 10.5" and 6" with grips in about the same place, 6" tiles. Ammo choice can make all of them effective for home defense, and IMO the 16" is probably the worst of the 3(also it's a 3gun rifle). a 10.5" with a K can ends up a couple inches shorter, and the 6" in 300BO is tiny even with a mid sized can mounted, it is also the most pleasant to shoot, even with supers, and from Smokey's chart above has about the same energy as the 10.5", but it's main benefit is quietly and reliably launching large subsonic bullets at close range, and the other 2 can't do that.

 

[RFBfromDE]

No that you have tamed a 5.56 or 300 into a quieter, subsonic home defense tool, why didn't you just get a 9mm PCC?

 

[alucard0822]

No that you have tamed a 5.56 or 300 into a quieter, subsonic home defense tool, why didn't you just get a 9mm PCC?

5.56 isn't practical at subsonic velocities, so pretty much all will be supers, and a 77gr going about 2200fps out of a 7.5" will be at least as effective as a 9mm HP in the same barrel. 300BO is an entirely different animal, a 110gr going near 2K FPS from a 7.5" barrel is more powerful than 5.56 or 9mm, a 220gr going 1k FPS presents nearly an inch long x .3" side profile on yaw, and expanding subs can reach an inch and out penetrate 9mm through hard and soft barriers. Of course that is with less recoil than a blowback 9mm PCC, same capacity, and PCCs tend to have issues feeding HP ammo.

 

[Bisleyfan44]

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While certainly not the equal of the 223 or 300, a 33 rd mag of these in a pcc would be awfully comforting. Plus, low recoil and cheap practice.

 

[spoon059]

Seems like an effective way to clean out the suppressor, no? Expensive though...