300 Blackout

[243LPR]

Anybody shooting it in an AR? Whose dies do you use? Any problems or actual concerns you've had to deal with? I have an extra complete lower and thinking of going this way for the next build.

[BlueDog]

No experience with it in an AR, but have an ancient 300 Whisper barrel on a contender some where... It keyholes at 40 feet. It was from Fox River (TC's custom shop) and it has too slow of a twist. I did contact JD Jones about it, and he laughed and said "Let me guess...Fox River." He offered to rechamber it to one of his stouter cartridges, and I never did send it in. As for AR's, the only thing I've seen (besides a fast twist for sub-sonics) is keep it FAR FAR AWAY from your other AR's (223/5.56) at the range. I've seen more than one "kaboom" photo from someone unknowingly inserting a 300BLK magazine in a 223 and then chambering a round, c l i c k. Complete destruction ensues.

[geargrinder]

I love mine. It's my current favorite non-Savage rifle.

Carbine length, supressed, with a Nikon P-300 scope. Super quiet when shooting subs.

[DrThunder88]

I have a 9" pistol that I've been thinking about SBRing and getting a suppressor for. The gun shoots fine for having such a short barrel, but it's nothing to write home about.

I've not reloaded much for it. Lighter .308 bullets seem to evaporate from store shelves, and heavier ones are comparatively expensive. I've prepped a lot of brass using a HF mini chop saw, Lee sizing and trimming dies.

[gmohr54]

I am. I have an AAC 300 Blackout and the wife has a Core 15 in 300 Black out. Both are tack drivers and a joy to shoot.
For hunting we use Barnes Vortex 110gr bullets. For target they love PMC 147gr. Both have zero feed or ejection issues.
We are waiting for our tax stamps and our suppressors. Then time for some 220gr subsonics.

Gene

[243LPR]

I would love to be able to hunt with an AR but our state doesn't allow it. It would be a great tree stand gun as most shots are fairly close. I'd still like to build one though to complete the extra lower I have. That 110 Barnes should do a great job,I've nothing but good luck with the TSX's.

[kevwil]

I'm using RCBS dies for mine. I haven't had any issues with the dies. The only problem I ever had was when starting to load subsonic, I started too low and the action wouldn't cycle fully.

[Texas Solo]

I just built a 300BLK upper for pig hunting. It will be Thursday before I can get it to the range.
Load data is sketchy IMHO. I find conflicting data everywhere. Do your homework, start low.
Cutting down 223 brass and forming 300 brass is sort of fun.
I use RCBS small base, taper crimp dies. The dummies I've made with some 150gr FMJ hand cycle perfectly.
Mine's a 16". You'll find that all 300blk's are carbine length or pistol length. Mid length just doesn't seem to work.

[mikein]

I run a 300 Whisper on an AR platform, and it performs great. When I first began reloading for it, a couple of the subsonic loads I built would not reliably cycle the action, but I've tinkered with it enough that it is now totally reliable. It really does a number on the local feral hog population, and I'll be able to try it on deer when the season opens in November. Our deer here in Central Texas are small, so I'm thinking the Whisper will be take 'em down hard and fast.

[lal357]

I do 300 blackout carbine length suppressor bought now the wait i'm also thinking about doing a sbr in one

[bajeep93]

I load for mine. I use lee dies. Lil gun and 168 smk are what my gun likes. It's a 16 inch pistol length gas. My dad built one with a 16 inch carbine length gas and it is a lot more picky on the reloads that it will shoot. It does not like lil gun.

[Twostepct]

Bajeep93, any issues with the Lee dies? The RCBS small base sets are cheaper than regular dies, but the regulars are nearly double the cost of Lee for some reason.

[bajeep93]

The lee does work great. I have used them to make all my brass and have never had a issue with them. I have loaded about 700 rounds with them.

[Twostepct]

Ok thanks.

[thermaler]

The popularity of 300 blk in an AR has always been one of life's great mysteries to me. : ) To me it's like taking a modern platform and seeing how you can engineer it to get 30-30 of yesteryears' performance out of it. I'd save the money time, expense and ammo and just buy a good AK if I had to have a short cartridge 30/7.62 in a assault rifle. There's just so much you can get out of an AR 15's dimension tolerances. If I were building from the ground up (which I have done) I'd go no lower than 6mm--preferably 6.5--and no higher than 6.8. Purely my opinions; not steadfast rules.

[Wildboarem]

As for AR's, the only thing I've seen (besides a fast twist for sub-sonics) is keep it FAR FAR AWAY from your other AR's (223/5.56) at the range. I've seen more than one "kaboom" photo from someone unknowingly inserting a 300BLK magazine in a 223 and then chambering a round, c l i c k. Complete destruction ensues.

Correct me if I'm wrong, but how does one chamber a .30 cal bullet in a .224 chamber? If there was a kaboom it wasn't from chambering a .300 blk in a 5.56/.223 chamber. Bolt won't go into battery by about 3/8" and hammer can't engage firing pin at that angle. If its the other way around it will just bounce the .224 bullet out the end of the barrel. But it is good to keep your magazines identified with the different calibers.

[bajeep93]

I just tried to chamber 168smk and a 125 spritzer in my ar15 in .223. They will not chamber. The bolt will not close.

[Wildboarem]

Anybody shooting it in an AR? Whose dies do you use? Any problems or actual concerns you've had to deal with? I have an extra complete lower and thinking of going this way for the next build.

Getting back on subject, I just built an 8.5" pistol in .300blk. I went with the heavier full auto BCG and H2 buffer. I could also swap those two items out with standard parts if it didn't function. I haven't had that problem. It runs great with supers and subs but don't have a can on it yet.
I use Lee 3 pc die set for it. I've used SR4759 and IMR4227 and both function fine. It's all I could find but I am looking for aa1680. Haven't made my own brass yet from .223, waiting in jig. Very easy to load for so far. Some mags work better than others because of the internal ridges, just FYI.

[bajeep93]

Wildboarem. You did not say but I am sure this is obviously a pistol length gas system? My pistol length gas system seams to function everything with or without the can. I did put an adjustable gas block on it to try and help with being over gassed with the can on. I use pmags with mine. I bought 3 fde pmags and shaved the top of the ridge inside it. I only use these in the blackout and my black mags in my .223. They have functioned flawless in the 300 blk

[Wildboarem]

Yes it is a pistol length gas tube. I don't think you could go carbine length with an 8.5" barrel. From what I've read pistol length gas system is the way to go for rifles up to 16" barrels. Since its using magnum pistol powder and not a ton of it, it's more apt to be under gassed than over gassed. Which is the opposite of the 5.56/.223.
The .300 blk is a fun cartridge. I've only shot it off the Bench as I had a friend function test it with 40rds, then I immediately started load development.
Next Saturday the Wifey and I will be doing some carbine work and I'm going to put it through it's paces. I have 200rds of 148gr m-80 pulls over 17 gr of IMR 4227. Should be a fun day :)