Piston Driven 300 Blk- Will it work?

[Metal Mike55]

My brother has asked me to build him a 300 blackout for hog hunting. I've never built a custom AR before but I do have a great amount of experience with them and how piston driven rifles work. He will be suppressing it and more than likely shooting hypersonic loads. I plan to use the Adams Arms XLP Carbine length piston kit with the low mass BCG paired with an almost all BCM upper. BCM Standard 16" fluted barrel, BCM M4 upper receiver assembly, and the BCM KMR ALPHA 15 Handguard. He was wanting to keep the price around 1200-1300 dollars. I was hoping someone with some more knowledge or experience could tell me if these parts will work together? Will it cycle rounds? Will I need to modify anything? Will the piston clear the KMR barrel nut? What weight buffer will I need? Should I swap any parts for others? Will this setup be accurate if it works? Any help would be appreciated, and please excuse any gaffs I've made in the post.

[CRNA]

I think Adams arms web sight tells you what rails you can use

[Metal Mike55]

I never saw the KMR on the list of rails that will work or the list that won't work. Unless I just missed it somewhere.

[Benito]

May work, or may not.
A DI BCM setup will almost certainly work, though.

I think you mean supersonic. It's not gonna be hypersonic, unless he's got some kind of rail gun.

[Metal Mike55]

Yes I realize the DI setup would work easily and more cheap, but he specifically wants piston drive for the ease of suppressing it and no blowback. Also yes supersonic.

[civiliansheepdog]

Piston driven, supersonic hog killer? Why the hell a .300 when you could run a 6.8? 6.8 would do a much better job, especially given a 16" barrel.

[VIP3R 237]

Double tap

[VIP3R 237]

Yes I realize the DI setup would work easily and more cheap, but he specifically wants piston drive for the ease of suppressing it and no blowback. Also yes supersonic.

A piston does not eliminate blowback from a suppressor, and they generally are louder than a DI rifle. I have heard from reputable sources that the 300blk and an external piston is a no-go.

[Metal Mike55]

He looked at 6.8 but decided on 300 for whatever reason he had.

[Metal Mike55]

He's fired a DI suppressed AR and said he was getting his face chewed up by the blowback. I assume Piston would cut most of it out would it not? And I'm not sure because I've read one forum where a guy was using the Adam arms kit with a 300 and it would run supersonic fine but subsonic needed some modifying.

[civiliansheepdog]

It depends on the suppressor as well. Also, the Gemtech suppressor BCG is worth a look.

[LTMattyL]

In my experience the gas comes back down the barrel after extracting the spent casing...not necessarily from the operating system. I have a SCAR16 that gets almost as dirty and gasses me like my 14.5 AR. That is using the same surefire mini on both. I also think that the size of the suppressor has an impact on the amount of returning gas.

Personally I would go with the DI 300 blackout or have you friend shoot a suppressed piston AR to make sure it meets his expectations.

[Will_Power]

I think you mean supersonic. It's not gonna be hypersonic, unless he's got some kind of rail gun.

Not with that kinda attitude.

[Clint]

He's fired a DI suppressed AR and said he was getting his face chewed up by the blowback. I assume Piston would cut most of it out would it not? And I'm not sure because I've read one forum where a guy was using the Adam arms kit with a 300 and it would run supersonic fine but subsonic needed some modifying.

The "gassy face" effect totally depends on the specifics of the upper.

A DI upper with the proper gassing for the suppressor can have almost no extra gas.

The 300BLK in certain configuration will show very minimal change with a suppressor.

[MegademiC]

Was the gun he shot 300blk? 300blk is much lower pressure and does not blow gas like 223, based on that I've read.

[Auto-X Fil]

I've shot a bunch of 300BLK and 5.56 DI guns of varying lengths, with a bunch of different suppressors. A high-quality charging handle with a good fit to the upper and adjustable gas blocks have made all of them shoot with almost no gas to the face. The BLK is better than the 5.56, for sure.

In other words, a piston is not the fix. Spend the money on a good charging handle, do the RTV mod for insurance, and put on an adjustable gas block.

And try to talk him out of 300BlK for supersonic hogs. It will do the trick, but it's not the best round for that app. Blackout really shines when you want to run subsonic, and/or from a very short (8-9") barrel. For supersonic, 12"+ barrel uses, other rounds offer major advantages ballistically.

[civiliansheepdog]

In other words, talk him into a 12" ARP 6.8.

[El Cid]

Aren't the PWS 300blk rifles piston?

http://primaryweapons.com/store/product/mk109-rifle/

[eodinert]

Even if they are, they don't do anything that a DI 300 blk doesn't do better.

[Defaultmp3]

Aren't the PWS 300blk rifles piston?

http://primaryweapons.com/store/product/mk109-rifle/They're long-stroke pistons, rather than the typical short-stroke pistons like LWRC, H&K, LMT, POF, Adams Arms, etc. Dunno what difference that makes in this application, but the difference is there.

[Auto426]

Just a suggestion, but your brother might want to look into a Sig MCX in .300 BLK. They're a little outside of the $1300 he set his budget at, but he would be buying a gun that was designed from the ground up to run .300 BLK suppressed. They have basically the same manual of arms as an AR-15 as well so there's no need to worry about learning to manipulate a completely different platform.

[Tokarev]

Ruger is offering a 300BLK conversion for their new takedown piston AR. I have one and it has been reliable with supersonic and subsonic both with and without a suppressor. Ruger is still using their midlength gas system but the 300BLK has a larger internal gas block and expansion chamber. That must be the key to their success.

Sent from my GT-P3113 using Tapatalk

[TheChunkNorris]

Faxon also has a 300blk LSP. There's a company that is working on a SSP system but it's a 16" and I'm pretty sure it's going to be picky on ammo.

[El Cid]

Even if they are, they don't do anything that a DI 300 blk doesn't do better.

Thanks for the lecture. Too bad I never said they did. OP asked about 300BLK piston rifles. I provided a link to one from a reputable manufacturer.