300 Blackout AR15

If I do switch I need a 10.3 " so its a simple barrel swap on my old well worn mk18 ish gun
 
I have a 9" 300blk, barrel by suputin.

Brass is cheap and easy to make, shoots 110gr to 220gr (i know you can go heavier)

I shoot 150fmj which are cheap, might try some cast.
 
7.62mm said:
Soooo.....at the risk of sounding completely stupid.......

What are the major benefits of this cartridge?
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larger calibre round in a .223 case so you get to use your existing .223 mags. You also get retain everything on your AR except the barrel.
Its very capable in subsonic making it less harsh on your ears. I think thats all.
 
Evil evil man Suputin, another bunch of converts today I think. Felt bad I didn't call 757Fixer to join in.
 
Suputin said:
I run a 10" BLK and I also have a 7" BLK upper. IMO the BLK is best in the 8-10".
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Now I remember a previous PM conversation we had going Sup :redface:

Shame we can't utilize this round as it was originally intended & designed for (suppressed).
 
Converting 223 brass is easy, I went to princess auto and bought a 6 inch chop saw and cut off 700 pieces at the neck. Then deburred them on my RCBS case prep center. Then run them through the sizing die. Then trim to length and inner/outer chamfer case neck. Time consuming but worth the effort and you don't need to do it all at once. I did a couple hundred just to get shooting then finished off the rest a hundred at a time.

Even without a suppressor the 208gr subsonics are quite quiet. They really hit the gongs hard to which is fun.

I'm really excited to get a non restricted barrel in 300BLK built for my ACR.

I've also bought factory loads for $16/box so it's not overly pricey to shoot if you don't reload.
 
Easier than the chop saw method. If you have access to a lathe, a buddies lathe, a buddies buddy that works with a lathe. Chuck the brass in the jaws (gentle now....), and I used an end mill to trim down to approx .020" above case length, run em through the sizing die, and then my Lyman case trimmer to finish them off. And of course I used a neck chamfering tool. Takes about 1min each to finish per brass. By far the easiest and probably safest way to use .223 brass for the .300 blackout. I use mine in my bolt gun with 168gr Hornady match hollow points. Love the thump on steel!!!
 
Instructor1 said:
Easier than the chop saw method. If you have access to a lathe, a buddies lathe, a buddies buddy that works with a lathe. Chuck the brass in the jaws (gentle now....), and I used an end mill to trim down to approx .020" above case length, run em through the sizing die, and then my Lyman case trimmer to finish them off. And of course I used a neck chamfering tool. Takes about 1min each to finish per brass. By far the easiest and probably safest way to use .223 brass for the .300 blackout. I use mine in my bolt gun with 168gr Hornady match hollow points. Love the thump on steel!!!
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I did exactly this. Even built a jig to help position the brass so I'd get the same trim length every time. It is too slow though. The chop saw method is way faster.
 
We've already started working on a jig that will hold at least 100 rounds for a mill. if we make 4 jigs that's 400 rounds at a time.

But wouldn't a Giraud case trimmer work too?????
 
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