Subsonic AR, .300 BLK vs. 7.62x39 input wanted

[KalamaMark]

End goal: I want to build a 16.5" OAL AR Carbine, utilizing a pistol length barrel of approximately 10.5" and a permanently attached Form1 can to bring OAL to 16.5"

Intended uses: Primary 'Bump in the night' weapon for two or four legged predators, inside or outside my rural home. Recreational shooting without hearing protection. Throw it on the quad weapon when working on the property and threats or recreation arise. Possibly use for deer hunting.

Quandary: Go 7.62x39 or .300 AAC Blackout.

7.62x39: I've built and own a 7.62x39 AR, and it took quite a bit of tuning to get it to run right. Subsonic loads are expensive if available over the counter. Subsonic load data for 7.62x39 is sketchy, brass is expensive, and I don't get the warm fuzzies that I'll be able to develop a load to run 100% through an AR. Special mags needed.
Pluses: Supersonic ammo cheap and plentiful. Pistol length uppers cheap through Model1.

.300 AAC Blackout: Factory subsonic loads readily available. Subsonic data readily available. Brass readily available and cheap. Parent brass readily available if you want to roll your own. Factory mag usage with no mods. Barrels reasonably priced if I retrofit a 5.56 upper. Cons: I haven't rebarreled an upper before, so there's a learning curve and a parts and tool investment. Lack of cheap, bulk, loaded ammo. Newer cartridge with short track record.

Any input, thoughts or experience on such things are wanted and appreciated.

Read More

 

[Nwcid]

The .300 (whisper, 300-.221, .300 Fireball, .300-223, AAC, ect) has been around for 20 years and has tons of data out there and a long track record. Calling it an AAC is the only thing new. Load you own is as cheep as cutting down .223 brass and loading with bulk 150gr .30 cal bullets (supersonic).

As for swapping barrels you will need a barrel wrench (~$25), vice block (~$40) and torque wrench. Pretty simple.

Since you are building your own can might be a fun project. I do have 1 gun with an attached can but for the most part I really prefer detachable. Plus that is $200 just in taxes tied up in one gun. Not knocking your idea, just saying.

Silenced guns, like any other, have advantages and disadvantages to "defensive" situations. One night had some dogs in the yard, grabbed the integral suppressed 9mm AR to go see what was up. Problem with having it suppressed is you can not kick off a couple "noisy" rounds to scare them off.

Here is a pic of my 16" .300 with 9mm Trident can;

 

[nubus]

I messed with running 7.62x39 subsonic and finally gave up and went to 300 Whisper. Now I shoot 300 BLK and am so glad I made the switch. The 7.62x39 was finicky and the mags drive me crazy. The 300 BLK is a great load and uses all common components. If you load it, it's plenty cheap enough to shoot too.

 

[KalamaMark]

I hear ya on the permanently attached $200 deal. I really want to keep the barrel length as short as possible, though. One possible option I've thought of is purchasing or fabricating a permanently attached shroud, like the Tactical Solutions SBX setup, to keep the barrel length legal.

Any regrets, do overs or input on the .300 build?

 

[KalamaMark]

I'm glad you chimed in, Nubus. You were on my short list of vendors to go to for my build. I'd be really interested in a Magpul kit price with a 10.5"-12" .300 pistol barrel, if you have any sources on such things.