Randy11;
Here is where we get to the fun part'RECOIL. The standard factory load of a 300 grain bullet at about 1800 fps is very mild to shoot in the Marlin. If you handle a 7mm mag, you can increase the 300 grain bullet to 1900-2000 fps and should have no problem. At that velocity that load is a good deer load out to 200-250 yards if you sight in 2 inches high at 100 yards. Not to much drop.
Now for the butt kickers, that will be the 405 grain and larger. If you load the 405 grain to 1800 fps or more, you are going to notice the recoil with a light weight Marlin, it will kick like a mule. I loaded some Rem. 405 grainers with 55 grains of H4895 powder for about 1900 fps in my Sharps. That load was a kicker in the Sharps which weights in at 11 pounds, the steel butt plate did not help either. This load will rattle your teeth in the Marlin, I would reccommend replacing the Marlin pad with a Pachmayr Decelerator pad or a Sims Laboratory "LIMBSAVER" recoil pad to reduce the recoil.
Another thing you can do is switch to a Hornady 350 grain interlock flatpoint bullet and use the same powder charge from the 405 grain load. This 55 grains of less bullet weight makes a big difference in the recoil. The Hornady bullet will do very fine on elk-bear-moose. I killed a 1600 pound buffalo with a single shot using that bullet and load of 55 grains H4895. My two hunting partners also used a single shot to kill two other buffalos with that load.
Another route is to use hard cast lead bullets, you can get them from 300, 350, 405, 500 grains. I would stay with the 300-350 grain and load them up to 1800-1900 fps and they will take anything from deer to large bears or elk.
You can find mild to butt kicking loads for the 45/70, just try different loads to find the one you like and can handle. Just remember that the 300 gr. hollow points are for deer size animals only, they expand to much and will not give enought pentration for anything larger, my son found this out on a wild feral pig that got away from him due to poor pentration. He now uses 350 gr. Hornadys or 300 gr. hard cast lead for his pig loads.
RELH