Barrel Compatibility Issues -- Mossberg 930 vs. 930 SPX?

[Specialized]

I have a Mossberg 930 SPX, the model that came with the potato-masher breaching barrel. It's always fired just great and never malfunctioned for me. I wanted to use the 930 as a multi-purpose platform for hunting, 3-gun, and home defense (or whatever else I felt like defending ), so I got on the Mossberg page and purchased additional barrels for it, the cantilevered slug barrel for deer hunting and the 24" smoothbore for turkey and upland game. I also purchased the 18.5" home-defense barrel, because I wasn't fond of the breacher barrel (while it looks kinda cool for the first several minutes, it looks very Tactical-Timmy to me after that). All of these barrels have functioned just great and I've gotten some good use from all of them.

Since I didn't have a use for the original breacher barrel anymore, I decided to sell it. Imagine my surprise when the poor INGOer who bought it couldn't get it to cycle with his 930! We had to go to Mossberg for answers, and it apparently comes down to this: the Mossberg 930 and the Mossberg 930 SPX are somehow different, and you apparently can't run a 930 with a 930 SPX barrel. Now I don't know what the differences are, hence this post; if anyone can shed light on this, I would appreciate it. For our sale transaction, I ended up refunding his money and he sent the barrel back. We're both a little smarter on what we bought now, too.

Can anyone tell me what is different between these two guns, and why on earth Mossberg would do this? I don't want to continue running my OEM barrels (which I bought from the maker of the gun, who has NO information on this topic on the spare-barrels page) if it's going to hurt the gun, and anyone that buys an SPX barrel for a regular 930 won't even be able to cycle theirs. Any ideas?

 

[kabob]

I have a Mossberg 930 Tactical/Home Defense and the barrels should have been interchangeable according to the manual. I'm confused myself. The difference in barrels is between the 930 and 935, again, according to the manual. Also, your SPX came from the factory with the breacher barrel? It should have come with the standard barrel with a pinned fiber optic front post. Like so:

 

[Specialized]

It appears to be an issue only if you have a 930 waterfowl or deer gun. But that makes no sense to me, because it seems like all of the components that would control the gas flow, and therefore the barrel functioning and being able to cycle the action, are in the barrel assembly -- piston, gas ports, spring, etc. I don't really see how 930 vs. 930 SPX would make a difference. I'm going to call Mossberg and ask their support folks what would make that happen. Cuz I clearly don't get it.

 

[Simonsez]

If I read your post correctly, it sounds like you bought the Tactical model with the breacher barrel originally. I just bumped into this post, so sorry for the belated response. I have a stock 930 that has seen a couple of barrel transformations- long story short, I had sold a HD barrel 18.5, got a turkey barrel, then in the end, decided I wanted the short barrel again. I got a Tactical breacher barrel from someone on the Mossberg owner's site.
Lo and behold, the gun would not cycle!. Seems the issue is the Tactical / breacher barrel is a heavy barrel with the welded heat shield, and for whatever reason it can cause problems ejecting and cycling. The fix was fairly simple: just tighten the forend cap all the way down (finger-tight), then loosen it a couple of clicks. Then the problem simply went away. Someone on that site ran into the issue, and had the fix. The only thing I could see was the fit into the chamber was ever so slightly different. Hope that helps. I did not like the weight or the feel of the Tactical barrel with the stupid breacher and it got sold last year.

Any variation of barrels has worked on mine with the exception of that one, requiring the 'fix'. I only have the turkey now, but if someone has the HD defense stock barrel I would be interested. Right now my turkey barrel does anything I ask of it, and I use improved cyl. - XX full and patterns are fine.

 

[Fujisawa-sensai]

Yeah I think I have the same problem. Just got a Mossberg 930 28" camo barrel from mossberg.com, but it doesn't quite fit my 930 Tactical model. There's about a 1/8-1/4" gap between the edge of the chamber and the back end of the vent rib on the barrel, and the little pimple on the inside of the barrel that the bolt runs past inside the chamber is about the same distance too far (compared to the stock 18.5" barrel) from the bolt when the bolt is back. Also there are only 3 threads exposed at the end of the mag tube instead of 5, but I can still get the cap on tight, and the gun feels sturdy enough when assembled.

At first I thought I just wasn't pushing the barrel in hard enough, but I can get the 18.5" barrel to seat with very little effort. The only possibility I can see is that the very back end of the barrel is getting caught on something surrounding the bolt. Maybe it's a little thicker at that end than the stock barrel?

I don't think there would be any safety issues with firing it... there's no open space where the chamber meets the barrel so no gas should escape with the cap on tight. The problem I can see is that the bolt goes further forward when it closes so it might be hitting areas of the chamber that it normally wouldn't. Also it has further to travel so it might not eject and feed properly.

The fix was fairly simple: just tighten the forend cap all the way down (finger-tight), then loosen it a couple of clicks. Then the problem simply went away.

That sort of lines up with what I'm observing here. The Tactical/HD barrel probably goes too far back into the chamber on a regular 930, and loosening the cap allows it to move forward when a shot is fired so it's in the same position as the longer barrel would be. Having the barrel moving back and forth during firing may not be that great though...