Matt,Did the quick set epoxy work for you? On my Prod arrow gun, I was blowing out the field tip and inserts like crazy, I used Loctite 609 retaining compound with Loctite 7471 primer on the arrow & insert and finally some success without shooting bolt parts everywhere. My Prod shoots 2219-20 bolts @ 444grs at 275fps = 74.5 fpe at the muzzle
i had a harpoon but i sold it on ebay just to heavy to hunt with imo