300 Black out or 7.62

Have not, it’s actually being turned into a 16” with a proof barrel now. It ran flawless without the can, spotty with. Didn’t feel like continuing to troubleshoot it.

 

X2 for the 300 Blackout as your caliber of choice. It was designed with an AR-15 platform in mind, hardware and accessories are plentiful, and it performs well through short barrels.

However . . .

You mention that your purpose is building a collection of plinkers for range use. In that case, I wouldn't build anything other than the .223 you already have. When it comes to punching paper and ringing steel at the range you're really not going to notice much difference between a 223 and a blackout. However, the 223 will be cheaper to shoot, and you will have a wider selection of ammunition available.

I suggest only building a blackout when you are planning a silenced build, as some of the other posters mentioned. Also, only stray from building a 223 when you have a specific purpose in mind, such as a 450 bushmaster for hunting, or a 6.5 grendel for long range use. Otherwise you're not getting much value above and beyond the 223 you already have.

 

True

 

Both my psa builds have been fine...but I have heard negative stuff about em.

 

Well I do want it for the same reason I got a rear bumper "just cus" lol

 

IMO barrel and trigger contribute most to accuracy performance, aside of general reliability. I wouldn't say my budget builds where just as good as my friends' high end builds, but they where good enough for the money.

 

I'm not sure what they're talking about because my 7.62x39 MK107 PWS Diablo upper (7" barrel) will blow fire like a dragon. Literally a basketball sized fireball at night or in low light situations is clearly visible.

With that said, I would go for a 7.62x39 setup. Ammo is cheap and plentiful, and it gives a much greater punch if you plan on hunting anything w/ it. I run shit russian ammo and have never had an issue a few thousand rounds later.

 

7.62x39 was developed for a 16"+ barrel using about 26gr of powder on a 123gr bullet, so when you shoot it from a 7" you are burning a lot of your powder in a fireball outside of the barrel.
300blk was developed for a short barrel and a can, so it uses less and faster burning powder (about 18gr for a 125gr bullet).

 

Exactly my point, w/ the fireball comment. My recommendation for x39 comes primarily because it is so much cheaper to shoot. .300blk seems rather pointless if you're not running a suppressor. I will say the MK107 has been a lot of fun and is fairly accurate at 100 yards shooting cheap russian ammo. Can hit steel at 200, and is useless any further out. Cheap and fun to shoot.

 

^^^^^^THIS IS THE ROUTE TO TAKE^^^^^^^^^^^^^^ 300 Blackout runs real good in this platform. It will knock a Wild Hogg on it's ass @ 100 yards. DOA

 

Have you shot the MK107 on paper? What kind of groups are you getting? I've never shot a short x39 with a US made barrel.
How has feeding reliability been with the curved-to-straight mags? I've read they can be problematic because the sharp tapered cartridges get out of alignment going up a straight mag well.

 

2.5 MOA @ 100yds and 2MOA @ 50yds. I’ve never had any feed issues but I did some research before I dove into the AR x39 setups and have exclusively bought C Product Defense magazines. I wouldn’t recommend anything else as I’ve seen feed issues like you mentioned with others.

 

I still dont know if I can run both sub and supersonic in the same gun.

 

The issue is balancing your gas impulse (gas port size) and your maintained gas pressure before the bullet leaves the barrel (dwell time). An adjustable gas block will help tune the gas impose. Adding something like a PWS CQB will help with the dwell time, but might not be crucial.

 

Yes U can

 

As @PacNW_Taco mentioned, I have a 300blk I built for backpack/EDC and using suppressed. I went with 7.5” and I “built” the entire thing myself. In my opinion if you want anything under 10.3” go 300blk. The only negative is cost per round. It’ll burn all of its powder in 8” of barrel so no huge fireballs. It’s amazing with subs and a can.


Fits nicely in a nondescript backpack.

 

I've run both sub and super through mine without a suppressor, a standard weight buffer and a non-adjustable gas block...not a single malfunction in 300 rounds.

 

That's pretty good. I was expecting to hear 3-5 MOA, that's been my experience. But most shorties I shot where cheap/plunking barrels or foreign made. Scope helps too, short sight radius doesn't help with precision.