I picked up the 22" Mossberg 930 JMPRO a few weeks ago. It runs pretty well, though I have had some issues with recent purchase bulk Federal 7.5 from wal-mart (failure to feed and soft primer strikes). Oddly enough. I have some of the same stuff from about 5 years ago that worked just fine.
My main issue is that the stock follower was getting stuck after the last shot and when unloading manually. Sort of like it was getting wedged tightly in place. When I would go to load the first round into the mag tube after this it required significant force to move. It would abruptly "break loose" resulting in my fingers crashing into the front of the loading port.
I thought it was just the cheap stamped follower being out of spec, so I ordered a GG&G follower. It's a great looking part. Unfortunately, I have the same issue, maybe even worse than the stock piece.
Has anyone else experienced this? Any ideas on how to solve this problem? Right now, I can't really even practice loading. I don't really want to have to deal with Mossberg either if this is an easy fix.
Thanks for the help.
UPDATE
I called Mossberg and spoke with someone named Dave. He said the mag tube is held onto the receiver with Loctite (I verified this visually) and that perhaps some of this got into the extension tube. He said to clean that area and try again. I did this and checked, but nothing changed with either the stock follower or GG&G follower.
After some fiddling and flashlight inspection, I determined that there must be a minor taper inside the magazine tube, perhaps minor compression from screwing into the receiver. This taper was creating a friction lock on the follower. I would estimate the effort to undo this lock was 10+ lbs of effort (estimating based on known trigger pull weights). The GG&G follower wasn't coming all the way to the receiver it was actually wedging into place about 1/8" shy of the end. The stock follower was stopping perhaps 1/32" or less shy.
What I did was chock up a cleaning rod in an electric drill with a 12G brush wrapped in terry cloth, applied metal polish and went to town on the magazine tube, focusing on the area just in front of the receiver.
I then ran a bolt through the small hole in the follower, locked it into place with a nut, chocked it up in the drill, and polished it as well with terry cloth and metal polish, focusing on the shoulder closest to the receiver when installed. I didn't do this to a mirror shine, just until it was noticeably smoother.
Well, it helped. There is still a little bit of initial resistance, but only a fraction of what it was. I'm going to shoot it before I do anymore polishing and hope things settle in after a couple hundred rounds. Loading after the first round is VERY smooth now. I would recommend everyone polish their magazine tube and follower on new 930s.
On another note. I'm not going to be able to use the GG&G follower. It's still getting caught up. In addition to that, it doesn't ever fully push the last round out when manually extracting. The shell will get wedged against the lifter about half way out and the bolt needs to be racked slightly to fully eject.
