Board Thread:Questions and answers/@comment-33092097-20190830191912/@comment-30049823-20190831000225

Ohhh, I think I see. It blocks the dart so the bolt sled doesn't just shove the dart down the barrel without getting a nice seal around it first. But yours isn't "opening the gate" once the bolt sled returns all the way to the front.

That's too big of a piece to just "go missing", so I'd suspect that either the "ramp" area of the tooth, or the part of the bolt sled that slides against it, got broken off or crushed. You may be able to "rebuild" the broken part of it, but resins and epoxies probably won't hold up. Try snipping off a piece of unnecessary ABS plastic from somewhere else, file it to the correct shape and dimensions, and bond that in place.

I'd keep an eye out for an old Longshot with bad seals or a tired spring, at thrift stores, garage sales, and local craigslist Nerf lots. It'll almost certainly be easier to find and harvest the part than to repair or construct it from scratch. (Probably cheaper too!)