The typical factory loads such as Winchester 300 gr go about 1850 fps and IIRC only 20,000 psi .Doesn't sound impressive until you hunt with it !! A big hole and youdon't need much velocity . I got a 300 lb red deer this year [preserve] and a Corbon 300 gr Barnes bullet smashed through both shoulders ,breaking up lots of bone and exiting at 100 yds.That's going 1900 fps.Need more than that ?
I laugh at the short range only comments when in the old days they used to have 1000 yd matches !
So typical factory loads can do more than you expect. Hot loads are hot on both ends.
I have a Browning 1885 about 12 years old .Very well made by Miroku .Originally 28" mine is cut to 22" ,you don't lose much velocity with the 45-70. the longer bareel guns only a benefit for black powder.Now a fine woods gun.
I also have a fine rolling block reproduction ,sadly no longer made .Lone Star Rifle Co ,it comes with a very heavy barrel so the 27" length requires a bipod.
In any case the 45-70 is much better than most think.