Not sure if this is the right location to post this or not but thought I’d reach out.

Long story short, my buddy recently purchased a 106u and had SBRd it and got the barrel threaded and left it at 10.5”. He installed a KNS piston and the model was the one made for the 107ur (he was told I would work and I did fit). He went to shoot it yesterday and was firing white box Winchester ammo and the firearm would not cycle without the suppressor with the piston all the way open and all the way shut. He put the can back on and it would function just fine. Does anyone know why this is happening or how to fix the issue? Thank you!

I want to say there is a restrictor in the gas block. It was originally a 16" barrel?

My ((10)) AKSU is under gassed a little too with the KNS. The KNS has a little different geometry requiring a bit more gas anyways.

I know this is an old post, but just fyi the KNS piston even all the way open is not going to provide the same gas as a standard piston.