Gunsmithing 300 BLK cycling problem

[Charlie Papa]

I thought I'd throw this out there and see if anyone has had a similar problem or if anyone knows the best fix.

I put together a 300 BLK using a Wilson Combat 14.7" barrel, carbine-length gas port, and an Adams Arms gas piston system. The lower includes a collapsible-length buffer tube, standard spring, and Enidine AR-restor buffer. It cycles supersonic suppressed, but not unsuppressed, and doesn't cycle subs either way.

Solutions I can think of:
<ul style="list-style-type: disc">[*]Try a standard carbine buffer and possibly a lighter buffer spring.[*]Enlarge the gas port in the barrel. [*](Really don't want to do this) Scrap the piston system and swith to DI. [/list]
Comments and suggestions are appreciated! Thanks.

 

[Oddball Six]

Re: 300 BLK cycling problem

AAC actually has a warning on its upper pages around what you can expect for different kinds of rounds cycling the AR.

300 blk seems to ride the edge of reliability and when your configuration is not completely appropriate for the cartridge, you run into this situation.

I'd be interested in soem of the suggestions because I am thinking about going a similar direction.

 

[Captain Moroni]

Re: 300 BLK cycling problem

What muzzle device do you have on it? Mine wont cycle subs without the suppressor boosting back pressure. If you cant have a can maybe try a Noveske KX3 or PWS's version I forget the name. You may try and enlarge the gas port as well, but be careful its easy to make it bigger but tough to make it smaller if you go to far.

 

[Glen Seekins]

Re: 300 BLK cycling problem

I wouldn't worry about subs without a suppressor because thats probably only going to work with a pistol length DI system. If you want it to run everything then you will be way over gassed everywhere but subs un suppressed.

I am just now playing with a carbine length 16" barrel and they are alot more tricky than pistol length with the blackout. Im not going to even try a piston system. If you want to stick with the piston i would call the piston MFG and ask if they have a known working combination. or ditch the piston and figure it out.

 

[ewoaf]

Re: 300 BLK cycling problem

I think you have a lot going on there with adding the piston conversion to a carbine length system. I'd try simplifying back to a DI myself, but your thinking in the right direction. It'll take work to get it right.

 

[Charlie Papa]

Re: 300 BLK cycling problem

Yeah, I might be going to a DI system. I wanted to run a piston because my 5.56 is so dirty when running suppressed, but even with the piston, this is still very dirty with the 762SD. I don't expect subs to run unsuppressed, but I do expect them to run with the can on and supersonic to run either way.

 

[Charlie Papa]

Re: 300 BLK cycling problem

Any other insights/ideas/words of wisdom from anyone? Thanks!

 

[Pittsbuilder]

Re: 300 BLK cycling problem

I don't know a whole lot about the AR-Restor buffers, but the first thing I would try is to swap that out for a standard buffer... If that doesn't improve anything, I would probably switch to a DI system next. I know the piston systems run somewhat cleaner, but the truth is, so much of the crud in your action comes back through the chamber when running a can anyway, and there's no real way to run a supressed weapon without it getting filthy.

 

[Rancid Coolaid]

Re: 300 BLK cycling problem

Lube the bejeesus out of the BCG. When you think you have too much lube, put on just a little more.

 

[Charlie Papa]

Re: 300 BLK cycling problem

I'm definitely going to try both of those suggestions once I get back in town.

Pittsbuilder, welcome to the Hide! Sounds like you might be an EAA guy... In what part of GA are you?

 

[Pittsbuilder]

Re: 300 BLK cycling problem

Charlie Papa:

Thanks, and I am an EAA guy. Im in Hampton, South of ATL. Are you an EAA'er too? BTW, the BCG lube suggestion is a good one. If its a new BCG, often they are pretty tight against the Bolt until the Rings wear in a bit. If this is the case, Try running the BCG in a standard AR for a couple hundred rounds to break the bolt in. The last AR I built wouldn't even cycle M855 ball reliably for the first 150rds or so, now that the BCG has loosened up, it's flawless

 

[GT40MkI]

Re: 300 BLK cycling problem

I had to trim a few coils off the spring to get my 10" DI .300blk to cycle...looking for the method I used now...but basically I'd fire one round and see if the mag would catch the bolt on the stroke...mine was ejecting the case, but not going back far enough to grab the next round.

You're on to something with the lube too, but at the end of the 2 weeks of trouble shooting, I tried 3x bcgs, 4 different buffers and spring combinations and bunches of lube before a buddy suggested trimming the buffer spring.

Hang in there - the round (subsonic) performs about as well as a 230 gr .45 FMJ out of a 4" 1911, but the ability to follow up with a 110 gr round moving at supersonic speed is great.