This is a newly tested version of a match saver for a Spring Thunder. Both the STL and the SCAD file are included. Installation is for a model 5 Spring Thunder, and requires 2 6-32 x .5 flathead screws.

A match saver is a small attachment, typically used on shotguns in competition shooting. It allows you to effectively increase your magazine capacity by one, by mounting an emergency round next to the ejection port, to be swiftly loaded in. It's called a match saver because, in the case of target shooting, it can save the entire match if you reach the last target and don't have any shells left in the magazine or chamber.