This is one of the few points where I disagree with the estimable Mr Waters. I think it was pure stupidity to make a higher pressure round that's shorter than an otherwise identical low-pressure round.
It just invites an accident from some rube who believes if it chambers it must be safe. A lawsuit is inevitable.
One can buy a .375 and load it to any pressure level one desires. Dropping down in power is seldom a safety issue.
But trying to load a low-pressure round like the .38-55 with maximum charges, or -even worse- stuffing it with an entirely different cartridge just because it fits; well, that's just dumb.
Yes, I know that a recently made Marlin .38-55 is PROBABLY no different than a .375. But how can you be sure that the steel is the same, the heattreat is the same, the throat is the same, etc?
Can you fire a .375 in a .38-55? The correct answer is, yes.
Once.
