My next build is going to be a fun range plinker. I've got the AR gamut well covered from 10.5"-24" in 5.56mm and was looking for something new.

Ammo costs aside, my idea was to put together a fun gun that was obnoxiously loud, spits fireballs with every pull of the trigger, but with a practical range of no more than 100 yards. CQB ranges would be the sweet spot. I plan on punching paper, shooting some gongs and general plinking. I've got zero intention of relying on it as an actual PDW or serious competition bangstick. Just something to leave you with a big, $hit-eating grin on your face at the end of the day.

I know what to expect from the.5.56mm,  but have concerns with the 7.62x39 over possible corrosion issues, recoil and premature wear of parts from the .30 cal round and potential feeding/reliability issues. As for the .300 AAC, the caliber is a complete unknown to me. Sure I've read the various articles published in the gun rags, but have never actually fired a single round, let alone one from a 7.5" bbl!

Incidentally, I will be opting to install a stock. It's a simple thing for those of us residing in the Great White North, although most of our other gun laws are almost as crazy as California.  I'm debating between a NEA CCS kit, Magpul UBR, CTR, or going simple with a genuine Canadian Forces C8 stock that are currently residing in my spare parts bin.





 
 
 

I'd go 5.56.  7.62x39 in a shot barrel is very loud and you'll have more recoil then the 5.56 will have.  

I'm very happy with my Ballistic Advantage 8" 5.56 barrel.  

Short barrel in 5.56 without suppression would be worse I'd think.
Uncorking pressure of 10,5 would be pretty concussive.   7.75 worse in 5.56.

Might be true with your experience, but the 10.5" 7.62x39 upper I had was fkn brutal.  That's the shortest 7.62x39 I've shot.   Fireball and concussion were crazy.  I'd much rather shoot a 8" 5.56.  It was better with an A2 flash hider, but the brake isn't that bad.  I was running similar muzzle brakes on both uppers.

300 BLK is right in the sweet spot for that barrel length, but if you never plan to suppress it or actually shoot any moving things with it go 5.56. It's obnoxiously loud.

Yeah, I'm leaning towards the 5.56mm as well. I'm already set up for 5.56mm on my Dillon XL650 and I kinda know what to expect recoil/noise-wise thanks to my Swiss Arms SG-552. So there won't be any real surprises there, just grins! :)

If ammo cost is not an issue, and you already have some reloading supplies, I'd go with .300 AAC to broaden your horizons.

You can avoid the dirty 7.62x39, and the weak bolts and feeding issues that go with it.

That being said, my next build will likely be a 7.62x39 pistol, but that's because ammo cost IS an issue for me (I don't reload, yet), and I already have a healthy supply of x39 for my AKs.

The 300blk is a good fit for a 7.5". With a linear comp its like shooting a carbine barrel. I also have a 10.5" in 223 and with a Levang comp, same thing... no issue.

Like them both so much, I'm building a 7.62x39 in 7.5". Can't say how it handles...still a work in progress.

300blk would be good in that barrel length and the best choice if suppressed. x39 will be more obnoxious.... just add a linear comp or flash diverter to push the sound downrange.

My 5.56mm in 7.5 is pretty obnoxious but def hits the threshold of what you are talking about in terms of fun range toy. Any thought on 9mm vice 5.56mm/7.62x39/300 AAC?  

That might just be b/c I'm bored and looking at quarter circle dedicated glock mag lowers and stuff but it seems like an intriguing build just for fun.

On the stock front, may want to add the LWRC compact setup into the mix too if you are looking for short overall length (but with the ability to extend it if desired).  
r-
Ray

I came close to pulling the trigger on the .300AAC build, but ultimately decided that it didn't offer enough to justify getting geared up to reload for it. Unfortunately, Canada probably remains the only western industrialized country that still buys into the Hollywood perpetuated myth of "silenced" revolvers, (I know...) etc., being solely the tools of gangsters and assassins.

As a teenager in the late 1980s I had the opportunity to vacation in Europe. I was blown away by the sheer number of community/public shooting ranges, there were at least one little gun shop and gunsmith in every village and in many jurisdictions sound suppressors were legally required to combat noise pollution. The exact opposite of my experience growing up in rural Canada.


You guys down South have seen most state governments finally get a clue and relax restrictions on suppressors, especially for hunting. The minute Canada follows suit you can bet a .300AAC will be first on my list.


In terms of stocks, I'll take a look at the LWRC. The others I listed are stocks I have on hand for future builds or leftovers from past direction changes. As a happy surprise, I found a Gen 1 LMT SOPMOD stock in my reloading room this morning that I had completely forgotten about. So that's another option.

I have the following....

9" AAC 300BLK.....excellent short weapon.  Weights just under 7 pounds with suppressor mounted.

8.5" Noveske 5.56......Also excellent, but not as quiet suppressed due to the super sonic round.

For me the 300AAC does everything a 7.62x39 would do, so I stay away from the "KOMMIE AMMO" stuff.

+1 on the LWRC UCIW stock. They are great. You may need to remove the weights from the buffer if shooting subsonic 300BLK unsuppressed. The UCIW standard buffer weight is between an H1 and H2 standard carbine buffer.

As to the OP's original question, if you want lots of noise and big fireballs, 5.56 is definitely the way to go.

If you want something that has practical utility as a PDW inside 150 meters, or have any aspirations of shooting suppressed, then 300BLK is the best choice. 300BLK works well killing wild hogs, it will work well on 2-legged varmints if need be.

I'd stay away from 7.62x39 in the AR platform due to bolt failure issues and the difficulty of fitting curved magazines into the AR's straight magwell and having them function reliably.

With the new CP and ASC mags out there, magazine reliability on x39 is not much of an issue. Also, if you buy a LMT or Cason bolt, you are not gonna have any issues with bolt failures on the x39 either. Don't let those two issues bother you in the least. Not enough to worry about anymore. My x39 is as reliable as anything else I own and I run several different 556, x39.

Like my 7.5 X39 but it is probably not loud enough for you with the KaK flashcan I use. Ditto on the bolt and mag issues. Old news.

I use my 7.5" 5.56 for a .22 LR conversion.
AND it still runs 5.56.
Then I assembled one in 7.62 x 39.

Cheap ammo.

.300 blk not so much.

The 5.56 uses cheap ammo and mags, and makes beautiful flashes. With good eyes and good technique you can land hits at 300yds with it, within 100 it's fast and easy. Love mine.