Mossberg 590A1 FTF Question

[Griblik]

Hi guys -

Hoping to probe the knowledge base for some help on a problem I'm having.

Bought a Mossberg 590A1 new about 3 years ago. Have probably 200-300 rounds through it. Recently installed some new Magpul furniture on it. Since doing so, it has developed a last round failure to feed nearly 100% of the time, where the last round in the tube will jam in the receiver. (See attached picture.) All other rounds feed flawless. Never experienced the problem prior to installing the furniture.

While I was figuring out how to install the Magpul forend, I removed and reinstalled the magazine tube, and I'm wondering if the issue is somehow related to that, but I very firmly reinstalled the tube with a strap wrench and loctited it into place, it's not loose at all. I'm using a fresh extra power mag spring and GG&G aftermarket follower, which move smoothly and push the last round firmly into the receiver. I've had both of those pieces installed since I first bought the gun, and it ran fine with them before. The jam happens when the pump is moving forward trying to move the shell from the receiver to the chamber, not related to drawing the pump back or moving the round from the tube to the receiver. Any thoughts?? Thanks!

 

[edwardware]

It's been a couple years since I rebuilt a 500, so it's a little fuzzy. It sounds to me like either:
1) the rails were disengaged from the lifter. I memory serves a stud on each side of lifter is supposed to ride a cam surface on the rails, or,
2) the new furniture is interfering with something.

In either case, fear not! Get a schematic, disassemble it, take some pictures on the way down, clean it up, and reassemble. It might take you an hour to rebuild it, but when you're done you'll understand it better; and that alone is always worth the time and trouble.

 

[Griblik]

Thanks for the suggestions Edwardware. I agree with your initial thoughts, I just can't figure out how either of those things would cause it to only happen on the last round?

 

[horsey300]

Mine really launches the shell back, is the spring/follower weakened/damaged/displaced? If it's only the last rd, I'd say lack of "push". Try indexing a single rd out manually as you would unloading the tube without racking it. If it doesn't shoot past your finger I'd bet on the spring.