Building a 300 BLK

I hope I made the right choice. I have been going back and forth on a 300 BLK and 6.8 SPC. Well I ordered an 300BLK, AR Stoner, stainless steel, 1 in 8 twist, 16 inch barrel from Midway USA. Should be here tomorrow. I am turning my AR15 pistol into a rifle. Will be getting a A2 stock for it soon to finish it up. Not going suppressed just like the idea of a .30 cal. AR15 and can use most of the parts that I have from the pistol.

Congrats! I've got one too. Eventually, I'll SBR it. Hopefully my supressor stamp will be in soon.

I built one a few weeks ago and I love mine, Good luck and enjoy!

What is the best ammo for unsuppressed and where to find it?

RON55 wrote:What is the best ammo for unsuppressed and where to find it?

I reload, but if I were going to buy some, I'd look at Midway or Aim Surplus.
147gr is a good plinking round 110-130gr ballistic tip seems to be the choice for hunting.

This is the lowest price I've seen online:
http://www.southwestammunition.com/product_p/300blk147.htm

http://www.aimsurplus.com/product.aspx?item=AGU300SUPER

I reload .45 acp, .40 S&W, .45 Colt, .38 sp. never have reloaded any rifle rounds. Guess I can learn. Have some .223 brass that I was saving.

Ive been waiting on a barrel for several months now.
Been wanting to build a 10.5" SBR 300 BO cause most of my shooting is at night on the farm and a semiauto with subsonics that will cycle is the ticket!

I already have some 300BO brass ready. Just need a barrel and start some paperwork.

I have been wanting one and im bout to bite the bullet and get one. I already have a .223 upper...can i just buy a barrel and swap it out and go....what else do i need to do? check headspace? thanks for the help

SHANE704 wrote:I have been wanting one and im bout to bite the bullet and get one. I already have a .223 upper...can i just buy a barrel and swap it out and go....what else do i need to do? check headspace? thanks for the help

Barrel swap is the only parts difference. I bought my upper complete, so I can't speak to the head space issue....but I would think that it needs to be checked, especially if you are going to use the bcg that you've been running with the 223.

Got my barrel installed and fired with the pistol lower with the pistol buffer tube, buffer and buffer spring. It would not cycle. Put on another lower with a carbine collapsible stock and it worked like a charm. Just need a new complete buttstock.

Taking my 300BLK hunting in the morning with these little jewels...

What you hunting I thought it was Prim weapons season again?

Stryker6 wrote:What you hunting I thought it was Prim weapons season again?

Crap, you are correct sir.

Miker, those look like the barnes solids; if so, how well do they open up with the 300's lower velocities? Wondering.

Methos wrote:Miker, those look like the barnes solids; if so, how well do they open up with the 300's lower velocities? Wondering.

Those are the ttsx copper solids. My load has them running around 2050 fps average. Barnes told me that 1800 is the minimum. I've only shot these into water jugs to check expansion, and they open up fine out to 100 yards, which is about the longest shot I could possibly get in the wooded area where I'd use them.

My load is a copy of one Bill Wilson used when he was reviewing the 300blk.

Those look purdy!!

Im gonna end up cancelling my 10.5" barrel order and just get that one off midway.
Hows the accuracy on it?
I plan on just shootin subs but would like to shoot 110gr full power or something.

nonnieselman wrote:Those look purdy!!

Im gonna end up cancelling my 10.5" barrel order and just get that one off midway.
Hows the accuracy on it?
I plan on just shootin subs but would like to shoot 110gr full power or something.

I've got a fixed 3x compact on mine now instead of the 3x9 in the photo. At 50 yards, the group is less than 1 inch. At 100 yards, I can keep them inside of 2 inches and that's about as good as my eyes and the reticle will allow. Using the 50yd zero, its a little under 1 inch high at 100, but it starts dropping after that.Seems like they were dropping about 5-6 at 200. That's with the 130gr Barnes, and 147gr pulled surplus. The 147 plinkers that I load from pulled surplus shoot just like the 130 expensive ones in terms of accuracy at the ranges I'm talking about. I've only tested my subs for function and speed.

Once I get the can, I'll probably get a short barrel for it or maybe just another upper.

I have been playing with the whisper/blk "same damn thing" for years. The outlaw state bullets are the best for subsonics when hunting. The pride fowler .22 scope with ballistic reticle just about matches the subsonic trajectory , just a fyi;)

ETA: if you plan to sbr it down the road make damn sure its a pistol port barrel so all you have to do is rethread and open the gas a tad.

RON55 wrote:I hope I made the right choice. I have been going back and forth on a 300 BLK and 6.8 SPC. Well I ordered an 300BLK, AR Stoner, stainless steel, 1 in 8 twist, 16 inch barrel from Midway USA. Should be here tomorrow. I am turning my AR15 pistol into a rifle. Will be getting a A2 stock for it soon to finish it up. Not going suppressed just like the idea of a .30 cal. AR15 and can use most of the parts that I have from the pistol.

Got my last parts in today for my 300blk build. Everything together and went to sight the scope in . Had a box of Atlanta Arms and Ammo, 125 grain pink tip and box of CMMG 147 grain FMJ. The 125 gr. shot will and then came the 147 gr. Gun would not cycle. Went back over everything and all was all right. So I opened the gas port. Had to go to .125 to get the 147 to cycle. IF I want to shoot 110 or 125 gr. ammo what will happen? Will I need to get an adjustable gas block, no problem if need to.

Sounds like you either have a heavy buffer and or a gas problem. Is you gas in the pistol or mid position? Whats your bbl oal?