Need some AR help

[bowaddict40]

I'm thinking about building a 300blackout upper. I have a M&P 15 in 5.56/223 now. Will this matchup to a 300 bo upper? What ammo is it? What I understand is it is basically a 223 casing with a 30 cal bullet. Am I wrong in this? If you would build a different caliber for my M&P platform tell me what you would build and why.

[okrattler]

The parent case to the 300 blackout is the 5.56/.223 so you should be able to do what you're wanting to do.

[boh347]

Yes, the only thing you have to change is the barrel for the 300 AAC. Mags and bolt carrier assembly will work.

[dessl]

Yes it will work. You can also use your 223 bolt and mags.

[ted_kennedys_liver]

you may want to wait a bit to start the build. finding stuff right now is a real chore

[bustacap]

Best thing to do is get a complete 300blk upper and put it on your lower.
There is a gun show in San Antonio next weekend. Want me to pick up an upper for you?
I saw some for ~$585 at the one a couple weeks ago.

[Ecoboost]

Only real difference is the barrel. Like others said a complete upper swap is easiest. But if you want to just have a 300BO all you need is a barrel swap.

[bowaddict40]

Thanks guys. I appreciate all the advice. The reason I say I'm gonna do a build is because I know where I can get all of the parts. And they are good parts that I can get on the cheap. Again thank you all for he information.

[texag93]

Thanks guys. I appreciate all the advice. The reason I say I'm gonna do a build is because I know where I can get all of the parts. And they are good parts that I can get on the cheap. Again thank you all for he information.

Well, once you've bought your parts, share your source

[bowaddict40]

Well, once you've bought your parts, share your source

Not really a source just know a couple of friends wanting to get rid of a couple of parts.

[Loneaggie]

Pretty sure technically it's just a barrel swap. A complete upper would make it easy to swap back and forth though.