Been shooting my 1895 Marlin since 1977, when I bought it new.
Yep, no longer than 2.550 for overall cartridge length.
The late gun writer Elmer Keith often quoted 53.0 grains of IMR3031 under the 405 gr. jacketed bullet in late-manufacture 1886 Winchester rifles, and later the 1895.
In my own rifle, I found this giving excessive pressure signs. In my own rifle I set the max at 50.0 grains.
The moral?
Each rifle is an individual. Don't believe all the internet boasting about heavy loads in the 1895. Sure, your gun may take it, but you may be courting a demon.
Besides, such loads accelerate your rifle's wear.
Be extremely wary of any and all loads posted on the internet. I'd use only loads posted by powder or bullet manufacturers with long-standing reputations.
I've been accused of using "Trapdoor" loads in my Marlin, because I am perfectly content to drive a 420 gr. cast bullet at 1,600 or 1,650 fps.
But let's face facts: The old .45-70 black powder loads killed bison, grizzly, moose, elk and other large animals for decades, and none of those shooters felt undergunned.
Typically, this was a 405 gr. bullet at 1,250 fps and a 500 gr. bullet at 1,100 fps.
I don't see much sense in loading the .45-70 to maximum for taking game. Back off a little. The game won't notice the velocity difference and your rifle will last much longer.
My Marlin 1895 is 32 years old and looks like new, with the occasional scratch on the stock or bluing. It's just as tight as when it left the factory.
I've often wondered what the damage rate on 1895 Marlins is. Judging from some of the outrageous loads posted on the net by other shooters, it must be high.
Bullet placement is the singlemost important factor in hunting.
The Inuit kill walruses and polar bears with the .22 Hornet, by placing the bullet in just the right spot.
The 1895 is a great rifle and amply powerful. If you need more than a moderate load, buy a .458 Winchester Magnum.