I hunt deer with a 1894 Marlin in .44 Magnum. I use Winchester white box 240 gr. JSP. The advertized velocity from a 7" barrel is 1180 FPS. My Marlin has a 20" barrel. I did some math to come up with a ball park velocity, out of a 20" barrel. I figured if the Marlin barrel is considered 100%, 7" is 35% of 20", making the rifle barrel 65% longer. Would it be correct to assume taking 65% of 1180, then adding it too 1180, give me a ballpark figure for the velocity increase?.............<><Duce