I have owned several Rolling Block rifles and I have made three out of blocks of 4140. It is probably the simplest rifle action in existence. I am assuming your rifle is based on a #1 or 1 1/2 action. If it is a number 2 action, it would be dangerous to shoot with anything but the very lightest of loads.
There are two types of #1 actions, black powder and smokeless. If the former; keep your loads light. Ditto for a 1 1/2 action. Google up Remington Rolling Blocks and you can find plenty of info on how to tell them apart. You probably have an 1897 or a 1902 action, and they can safely handle any sane 219 Zipper load.
The only complaint most shooters have about Rolling Blocks is their agonizingly slow lock time. Getting a good trigger pull is easy enough, but that massive hammer takes forever to fall and there is a bit of "THUNK" when that three ounce hunk of metal finally comes to rest. But, what the hell, a lot of the fun in our sport comes from taking something that isn't exactly designed to do something; and then making it do that exact thing....and do it well.
Sounds like you have a Rolling Block that shoots like a target rifle and I'll bet you get a lot of positive comments about it at the range.