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willie
04-24-2018, 11:38 AM
Over the years I've experienced a few negative issues with shotgun mag extensions. One was shell deformation thought to be an ammo issue. The result was having rounds that would not feed. So I inspect for this situation now. Today I inspected my trusty 870 Marine Magnum that has a Wilson plus 2 extension loaded with Federal Premium l.e. ammo and discovered a problem. The follower would not push the last shell from the tune. It stopped half way. Immediately I knew that even the flex tab lifter would not work with this situation. In an emergency slamming the butt on the ground would have been necessary. Instead, I removed the shell from the tube with my finger but then noticed that the follower was stuck. Removing the spring and follower and then reinstalling the unit resulted in normal function. What happened? The follower is polymer, and I think that over time exposure to cleaning/lube chemicals caused a dimension change. This piece no longer travels as freely up and down the tube as it once did. But there's more to this malfunction. I think that the mag spring twisted when the extension was last installed. Spring strength is high and is not an issue. My remedy will be replacing the entire unit with a Vang plus one extension. Replacing the follower would suffice too.

txdpd
04-24-2018, 12:23 PM
You're spring probably got caught in between the end of the mag tube and the extension. On the end of one piece units like the Vang and Wilson, there's always going to be a gap between the end of the mag tube and the extension. If they flush fit then you run the risk of not being able to screw it down far enough for the detent to engage. Sometimes there's a burr on the end of the tube that will exacerbate feeding issues. Multi-piece units like the factory extension or nordic, won't have the gap, but may require a clamp to keep them from unscrewing (factory units can have their own alignment issues).

The polymer followers are notorious for getting embedded with crap and getting stuck. I think the Vang follower is a good choice. The tolerances on the Vang extension might be tighter than the Wilson, but it will have the same inherent issue.