the marlin is a stronger action and has been chambered in rounds that aproach 50000psi chamber pressure and can take ammo a bit hotter then factory with eaze. The 3030 is a round that is loaded conservitively by all the ammo manufactures and data in the books are conservititive too for the same reasons the 257 and 757 and many other rounds are loaded down. Even a new wincheter will take a bit more pressure then whats in the books. I wont give out loads I use that arent in a loading manual but its nothing to take a 3030 into spitting range of a 300 sav. Now whether your gaining any killing power is very debateable. Id say no. the bullets used in 3030s are designed to open up at lower velocitys anyway and can be a bit destructive even in factory ammo and pushing them is just going to make it worse. I would have to worry about penetration on anything bigger then a small deer with hot ammo. As to flatter trajectory a guy that knows his gun and load can easily take game to 200 yards with a 3030 using factory level ammo. If i want to shoot deer farther out then that im going to bring the proper tool to do it