Probably the biggest flaw holding back the Retaliator is its awkward top slide prime. Not only is it relatively uncomfortable (compared to most preferred priming mechanisms), but it's also a relatively awkward motion and gets in the way of aiming. The solution to this problem is, naturally, to convert the Retaliator to a pump action, and the included barrel piece is a perfect mounting platform.
Gavinfuzzy Customs provides one such pump grip.
