Unlike most centerfire and rimfire bolt guns, the B-Mag cocks on close rather than cocking on open. Also, the firing pin spring on the B-Mag is a lot heavier than your typical centerfire or rimfire as it needs to be to set-off the new nail gun based cartridge.

As for all the plastic, that (and the overall aesthetics) are what have turned me off to the B-Mag since the first time I saw pictures of it. Goofy doughnut hole bolt knob, goofy looking shroud on the back of the bolt, plastic trigger group assembly, yet another ugly synthetic stock with horrible ergonomics, etc.