Originally Posted by GrimSlayer
the G6R bolt will not work with the gen4 but i have heard that you could modify a Vice/Protege bolt to fit in a gen4 but if i were you i would just stick with the stock bolt.
Gen 5 and gen 6 use the same bolts.
I have a post around here somewhere showing how similar the gen 4 and gen 5 bolts are. Back when the gen 5's first released.