The basic design of the H&R action is not too strong and is susceptible to eventual loosening with the heavier, or high pressure rounds. Probably OK with the smaller, or low pressure calibers. I suspect if you go too heavy with a 45-70, that barrel will eventually be wobbling on the action. We used them as kids because you could buy a "Topper" for $25. I have one tucked in the back of my safe that has come off the face and and has an eight of an inch of barrel movement. I keep it for sentimental reasons.