I have just gotten a Marlin 1894s in 44mag cal. It wears a 20" barrel. I have a few questions. Is there any modification that can be made so that this gun will feed longer than standard bullets, 300+ grn BTB. Also need a good full power load using the BTB 280gr WFNGC. This is the bullet I shoot in my SRH. Also what kind of velocity should I expect with 280gr and 20" barrel