Hornady loads for the Marlin can easy go 45000 lbs. According to reloading manuals, Horady pretty much set the Max pressure of the Modern Marlin at 50,000 lbs. My shoulder sets the limit at a good deal lower than that. Loads at the top of the Trapdoor section will get your attention right away. Garret has done tests on the long wide flatnose cast bullet reaches its Max penetration at about 1600 fps. In thier tests the 45-70 penetrated 6 and one half feet in Ballistic testing material while the 458 Lott and 458 Win Mag penetrated only about half that. At higher velocities the bullets start to expnad and or stray off course bring penetration to a quicker stop. A 400 grain Cast bullet from LBT or Corbon will shoot through about any critter alive at 1500-1900 fps. The Marlin loads reach that level and more. Check out the Garret site if you have not already. Some good reading from people who know thier stuff. I load the Hornady 350 grain Round nose to about 1800-1900 fps but only if I really need a big bear load which this one is. The 350 Grain Speer will give the same type performance where thier 400 grain has a lighter jacket and is intended for deer and elk. The Wide flat nose cast causes a tremendous wound channel and penetrates beyond belief. A friend of mine while on a Bison Hunt in South Dakota accidently dropped two buffalo with one shot with the Marlin. And that with just trapdoor lever loads. Factory Reminton 405 grain Flat nose Hollow point jacketed bullet.