300 AAC Blackout

[ThePlinker]

Long but good -- Travis Haley 300Blk

[Bill D]

Thanks for posting this. If I can find an upper in .300 Blackout, I'm going to have a suppressed rifle.

[leemozoid]

From what I read, powder selection is critical so far as getting the action to cycle reliably with subsonic ammunition.

8.5-9.0 grains of Lil' Gun and a pulled M2 AP bullet with a tight crimp cycle reliably in my 9" build using a YHM 7.62 Ti Phantom suppressor.

Gratuitous video link. This is 220 Remington OTM subsonic.

[Rifleman WI]

I love my 300BLK. I built my 16" AR in 300BLK to make a nice light rifle for hunting on foot (so I don't ding up my M1 Carbine). I had some cycling issues, but all I had to do was open up the gasport to .125
I plan on building another in 10.5 and 14.5 when parts come back in stock.

[gmg1183]

A friend of mine bought one of theses uppers, but is having a heck of a time finding anyone with ammo. He has some back ordered from a couple of places, but a few weeks out.

[Rifleman WI]

A friend of mine bought one of theses uppers, but is having a heck of a time finding anyone with ammo. He has some back ordered from a couple of places, but a few weeks out.

That is the hardest part right now, I paid $25 a box last month for regular Remington Supersonics just so I could still shoot mine. They usually went for $11 a box before the scare.

[Bill D]

I finally bit the bullet and bought a CMMG in .300 AAG Blackout. I have been learning the best way to fabricate ammo since I got it. Loaded ammo of any type is impossible to find here so I'm going to roll my own from scratch. I was finally able to find a box of 150 grain HPBT Sierra bullets and by calling Sierra was able to find a powder that I had that they would suggest a load for. I loaded up a few rounds of resized LC brass with 16 grains of IMR4227 and Winchester SR primers and the aforementioned 150 HPBT Sierras and headed up into the mountains for a function test. I fired three rounds for effect and found the rifle functioned fine with them but the fired primers were a bit flat. Accuracy was outstanding with my old eyes and the plastic Magpul rear sight that came with the rifle. I have loaded up several rounds with 15.5 grains of the IMR 4227 and will take it out later in the week and see what they act like.

I really like the CMMG rifle. It seems to be the standard AR15 platform and looks as good as any of the rest of the herd that I own (Colt, Rock River, Olympic Arms). It came with a standard AR front sight mounted on a stainless steel 1-8 twist barrel and has a picatinny flat upper mounting a Magpul fold-down rear sight. The Magpul is good enough for an emergency but this rifle is getting a Leupold Tactical scope in 4.5X 14 power for a user. Like most other out of the Box AR's, it could also stand to be fitted with a better trigger which it will get. I also have a silencer/suppressor ordered. Paperwork is all done - just waiting on the Feds to bless it. My next project will be to continue my stamp collecting and cut the barrel back to 8.5" and find some 220 grain FMJ's and a powder to use with them.

And the hemmoraging of greenbacks continues.

[NASAman]

I read the article in Shotgun News and was very impressed with it and since I had just gotten a new receiver from my club I decided to build a copy of the rifle in the article. It has been a fun project and I have learned a lot doing it. I found that there are two different types of front sight for the AR15, a rail mount and a gas block mount. They are different heights. Of course I bought a rail mount and stuck it on the gas block since I was ignorant at the time and was hitting about two feet high at 25 yards. I have also had magazine issues and found that the older Mil-Spec metal mags seem to work the best. It does not like the plastic mags and I bought some brand new, in the wrapper Colt mags at a gunshow and they are of very poor quality and made from thin sheet metal and don't feed reliably. I have only shot a few rounds through it so far but it seems like this will be a fun gun for an urban defense weapon. Those urbans can be dangerous you know!