RE: Which mechanicals at 300fps?
Ken,
Hmmmm I wonder if the O-rings you used were old and had softened/dryrotted...I shot jaks several years ago at 290-300 FPS out of a Darton Hurricane with no issues...
Try 2 of the Rocket rubber bands....
Spitfires are hard to beat if you have energy to spare. Super sharp, good cut, good blade angle, very stout..just like the Jaks.