My 930 JM has been flawless cycling, but I did change a few parts before even firing it the first time.
OR3Gun's : Marine Tube Spacer, Follower and Recoil Spring Buffer.
You've gotta keep em clean though, at least that's what I've read.
I clean every 2 matches, or before an important one.
It's the cost of entry I guess, which I don't mind.
Lots of people overlook the gas rings when cleaning.
Also, I forget what the parts are called, but the spring and gas parts that do NOT come out of the barrel assembly, that area needs to be cleaned as well.
Also, when assembling, there is a little ring in said area that can get bound up causing failures. If there is ever resistance, when putting the barrel back on, start over and check everything.