What rounds are you using? Subsonics? Any FTE or FTF? Might help determine where it is failing. Try some hotter/weaker loads and see if you have the same issues. So you are saying that when unsuppressed, the bolt is going fully to the rear and loading new as it returns to battery. Then can on, does the bolt not go fully to the rear? At that point, your options are increasing gas in, reducing the weight of the bolt, or strength of the spring... but I'm somewhat surprised... Doesn't putting a can increase the length of the barrel thus increasing pressure/recoil/velocity of the round? If you are running with no gas being bled off, and still having cycling issues.... this will sound counterintuitive, but **my guess is that you might actually need a *heavier* buffer weight/spring to counteract the increased blowback weight/speed of the bolt cycling with the can on. It might be cycling so fast the mag/spring doesn't have the time needed to feed correctly.** I'd also try tweaking your adjustable gas block to bleed off more gas. IDK though. I'm no expert gunsmith but I dabble. https://www.silencershop.com/blog/post/common-silencer-cycling-issues https://www.ar15.com/forums/armory/AR_buffer_weight_when_suppressed_/20-385476/ I'd recommend getting somekind of variable buffer. https://www.odinworks.com/Adjustable-Buffer-p/os-abs.htm It's something you can try to tweak yourself, but unless you have tungsten/lead powder or other metals laying around with the ability to machine it as needed, the adjustable weight buffer kit is the way to go if you aren't quite sure what you need/want, and let's you test each type. imo at least.