[amafrank]

I don't have a Jap LMG in front of me but it seems that it has a hotchkiss like gas system if I recall properly. That means unscrewing the adjuster allows more gas to escape and reduces the pressure in the system. I may have this backwards but its worth looking at carefully to make sure you are really on the lowest setting. One thing to try is oiling the cases too. Don't over do as light is as good as heavy and won't gum up the guts. It has been said many times that there is no primary extraction with the jap guns but if you look at the locking system you will see that there is a slight amount of movement as the bolt unlocks. It may not be quite enough if the gas is up high though...


The langley conversion may be a tad short on gas to operate and its just barely catching the sear when you let go of the trigger. That might allow that extra round. I have no idea how you can pump that pressure up to make sure.

Just guesses on my part since I'm not the jap gun guy....

Frank

 

[amafrank]

Good videos Sam. I watched the video you linked to subguns and I'm with CR Junkie on this one. It looks like a sear or op-rod problem in the 7.62X39. Its a cool runner too.

As for the .308 I'd be careful not to do anything that will allow the op-rod to hammer the back of the receiver any harder than it does. Cutting mainsprings or substituting lighter springs may sometimes fix a symptom but invariably leads to more damage somewhere else. If the gun won't run with the spring thats in it something else is wrong. Putting a stiffer spring in shouldn't compromise running it should just speed it up or at worst prevent the sear from catching. I'd work with the gas system to reduce the pressure and check headspace carefully.

Good luck
Frank