300BlkTalk

First I am new to the forum so if this is posted in the wrong area or the format is wrong please let me know and I will fix it. Thanks for having me!!!

I have an 8.5 Anderson 300 blackout pistol. When I first bought it I had some cycling issues when switching between supers and subs. It was a mix between not cycling between rounds and failing to lock back after the last round. I was able to fix it by adjusting the gas block.

Fast forward to now. I have switched out the standard A2 to a noveske KX5 and added a law tactical folding adapter. No matter what I do to the gas block I can not get it to cycle from round to round or to lock back on the last round.

I have ordered a buffer spring from Nemo Arms that claims to fix the finicky 300 blackout gas issues.

Does anyone here have any other suggestions?

The correct buffer for a pistol is an H2 4.9 OZ, hopefully that’s what you have, the Law adapter adds 2 OZ which is too much weight without a suppressor. You should be able to use a carbine buffer 3 OZ, and be back in business.

If you already needed a carbine buffer before adding the LAW adapter, there is something else wrong.

Would this work?

https://www.deltateamtactical.com/ar-15 ... -3-oz.html

Also should I even bother with the spring I ordered?

that buffer should work - with your law adapter anyway. otherwise its too light.

i would weigh what you have now before you order, that might be what you already have (almost every basic kit ships with a 3oz buffer)

and no you shouldn't need a special spring. the system was designed to run on a standard spring. buying a special lightweight or heavy spring is putting a bandaid on not addressing the real issue.

So if I already have a 3oz buffer what would be the next option to try?

when you say its not cycling round to round... what do you mean exactly? failure to feed or failure to eject?

were there two different issues that are specific to supersonic and subsonic specifically or just random with both? for example: failure to bolt hold open with subs, and failure to feed supers?




clamp on gas block or set screw? if is the barrel dimpled?

do you have a small gap between the gas block and the gas block journal shoulder? most gas blocks need this as the port is designed to have the forward portion of a mil-spec foreend into a metal plate that rests between the block and the journal shoulder
(pic from da web showing example of correct gap)


where is your brass landing when ejecting when it does work correctly? 3 o'clock? 5 o'clock? this can help us determine if over or under gassed - both of which can cause last round bold hold open failures


can you give us a picture of a failure?


i'm sorry to ask so many questions, but theres quite a few possibilities that could be causing your issues, so more details will be helpful for the wizards here to diagnose your problem and point you in the proper direction to resolving it.

Sorry for the late response.

I don’t have any pictures right now.

When i first bought it and before I put the kx5 and law tactical on it I only had issues with it not holding the bolt back on the last round. I was able to fix it then by adjusting the gas between subs and supers.

This time I shot it after adding those things and only shot 120gr and no matter how I adjusted the gas it would feed round to round and the bolt would stay back on the last round.

Well the buffer I have installed currently is 3oz. Not really sure where to go from here.