Theres a chap on the PBnation boards that is manufacturing a new bolt for Cockers, called the Mutant. Its a bit like the freak of bolts in that you get 3 delrin front ends with it and you fit the best one for your marker.... apparently in tests its very very good... Im gonna try and get one sent over here and give it a go, seems they are especially good if you are running any sort of electro trigger due to it lowering the weight of the moving parts quite considerably..