The Mossberg 930 is a shotgun that is not as widely known or discussed as some others but it's truly a fine gun. I've had mine since early 2011 and have put hundreds and hundreds of rounds through it. I've shot everything from 2.75" clays loads to 3" turkey loads and as of this date, have never had a malfunction or failure to feed of any kind.
I did thoroughly clean it initially, deep cleaned the bore, etc. but really have performed very little other maintenance to it otherwise.
I've spoke with Jerry Miculek and Patrick Flanigan since they both started shooting different models of the 930 and they've both had the same experience that I've had about reliability. Jerry uses his is competition, having switched from a Benelli and Patrick uses his in exhibition shooting after switching from Winchester.
There is a common thread that I've seen that emerges from shooters of this gun. The first is the reliability of the gun and the second is the speed of the gun. You can put out shells as quickly (more quickly for most of us) as you can pull the trigger. I never attached much importance to being able to fire a shotgun very quickly but it does demonstrate that it just doesn't jam easily, if at all.
I've also been very pleased with the workmanship that I've seen in this gun. The bore is slick and shiny, the fit is good everywhere and the trigger is very good for any production gun.
It also comes with a shim kit that allows adjustment of drop which comes in very handy in making fit adjustments.
I chose the subdued finish and black synthetic stock model with a 28" barrel (waterfowl model) but there are 15+ different models available including some specialized models that include modifications made by competition and exhibition shooters.
It's just a very good gun, reasonably priced and one to consider if you're in the market for a self-loader.
Thanks,
Clark