7.62x39 vs 300 Blackout

[Trinimon]

Okay ,thanks for that .............


I was more interested in if there was a reason for one length over the other with the .300 , from what little I know and read about it , it likes the shorter barrels , mostly because of the fast burning pistol powder it uses , again , just from little reading on other forums , so with out barrel restrictions why would you use a barrel longer then 10" ?

I'm thinking of getting a .300 blackout barrel , just something to try it out , just because , so , what's an ideal barrel length for the .300 ?

Whoops, my bad. I misunderstood your question. I thought you were referencing barrel lengths that made ARs restricted or NR.

From my readings, the optimal barrel length for 300BLK is 9" and that there really isn't any huge benefits beyond 9" in the 300BLK. We're talking approx 300fps faster from 9" to 16" barrel using 110gr pills. That said, the SAAMI standard for the AAC 300 Blackout cartridge is listed at 16".

Here's what they say on AAC's website, "Max effective range, using M4 military standards for hit probability, is 440 meters for a 9 inch barrel, and 460 meters for a 16 inch barrel. "

Here's some reading material... http://300aacblackout.com/resources/300-BLK.pdf.

 

[Sqr]

I bought the 6.8 pmag at Tier One Armoury in Edmonton.
You can only buy ACR's in 223 right now. All my conversions are custom built.
I've run my ACR 6.8 barrel in an AR but haven't tested it in my ACR yet. It's a Questar stainless barrel like my 223 NR barrel, I had a 223 bolt opened up to use with the 6.8.
Any AR barrel with a midlength gas system will drop right into an ACR. The ACR gas system is more efficient than an AR though so you want a smaller gas port than an AR would have for that caliber and barrel length.

Have I got it right that you said an AR barrel can be used in an ACR? What Mods are required and is the barrel extension identical? On the ?Bushmaster web site it displays 6.8, 300, 7.62 and 5.56 conversions. If you don't mind where is a good dealer for an ACR?

 

[cr5]

Have I got it right that you said an AR barrel can be used in an ACR? What Mods are required and is the barrel extension identical? On the ?Bushmaster web site it displays 6.8, 300, 7.62 and 5.56 conversions. If you don't mind where is a good dealer for an ACR?

The ACR uses the exact same barrel as an AR except it uses a midlength gas system and has a notch cut into it for the op rod guide. My 300BLK conversion uses a pistol length gas system and I eliminated the op rod guide.
The only other difference between them is the ACR piston system doesn't require as much gas to cycle. When I put the factory 16 inch ACR barrel I had laying around into an AR I had to open the gas port slightly to get reliable cycling.
Their website says a lot of crap but the 16 inch 223 is the only factory barrel that has ever come into Canada.

For hunting purposes, I keep looking at the 300BLK as an updated 30-30, with the various bullets available for it. A deer and yote gun to about 250 yards that is a pleasure to shoot.

I wouldn't shoot at a deer beyond 150yds with the 300BLK, at the lower velocities reliable bullet expansion is questionable with most types of bullets available to us as most 30 cal hunting bullets are designed for 308win and 300 mag velocities not the velocities 300BLK is running at.

 

[Greenhorse six]

cr5 , Suputin , Thank you for the info , good stuff .

Tinimon , I feel like an * , I should of went in to more detail on my first question , good article , thanks .

 

[f55]

300blk = $1-$2 a round
7.62x39 = $0.20-$0.40 a round

it all comes down to how much you want to shoot

My reloading and casting equip was paid off years ago. I cast 230gr for 300blk, it costs me $8 per 50 rounds.

I could also cast and reload 7.62x39 but the issue is brass, 223 brass is free.

casting,powder coating and reloading 100 rounds takes about 1.5 hours if i take my time.

 

[zxcvbn]

Is that the Remington Tactical 300 Blackout bolt action you refer to?

Btw, I appreciate your informative posts You too Saputin

FWIW I have a custom made 300 BLK bolt gun built on a Rem 700 (17 Fireball) action that is in a Cadex chassis. I also have a 7" PDW AR as well as a 10" AR and a 12" NEA AR all in 300 BLK. I built the 7" and 10" bbls myself.

The 10" AR is running a Law Tactical folding stock and a custom built, fully adjustable captive recoil spring system. The 12" NEA is pretty much stock as it just gets used for testing ammo etc.

Pics?

But no worries if not, just curious how you guys are building

Especially interested in the bolt action i.e. non-restricted builds

Not sure what you are after? Guns get built the same way any gun gets built. Start with an action, buy a bbl blank and turn it on a lathe. It's pretty straight forward.

As you can see, I'm interested in bolt action builds. You mentioned a Cadex chassis. That is what I was I was interested in seeing pics of i.e different bolt gun setups for 300 BLK. Perhaps I'm sick of being regulated But thanks for the lesson anyways. I had no idea they were built that way...and my apologies if I appeared stupid...

 

[goose705]

7.62 x 39, which mags will work best for these and whats their availability? New to ars and thinking of buying one in 7.62(black friday strikes again). If I can't get appropriate mags theres no point. Please point me in the right direction. thanks

 

[cr5]

7.62 x 39, which mags will work best for these and whats their availability? New to ars and thinking of buying one in 7.62(black friday strikes again). If I can't get appropriate mags theres no point. Please point me in the right direction. thanks

XCR-L pistol mags work decently for most people but not for all. The problem is that the straight AR mag and the heavily tapered cartridge of the x39 don't work well together, it's usually ok for up to ten rounds but some guys have had issues with the pistol mags. Magpul is also making a pmag now with a heavier curve specifically for the x39 cartridge. These are unfortunately limited to five rounds but should be more reliable.

 

[mikethebike]

XCR-L pistol mags work decently for most people but not for all. The problem is that the straight AR mag and the heavily tapered cartridge of the x39 don't work well together, it's usually ok for up to ten rounds but some guys have had issues with the pistol mags. Magpul is also making a pmag now with a heavier curve specifically for the x39 cartridge. These are unfortunately limited to five rounds but should be more reliable.

pinned to five rounds of 762x39?

 

[cr5]

pinned to five rounds of 762x39?

Is that a question?