What is the recoil of the 45/70 like? And what is its closest caliber comparison with recoil?

Got a lot of range there with that caliber depending on what loads your using, and what rifle.
It can be anything from a manly kind of push to a teeth banging hell raiser.
Factory loads out of a marlin lever action witha decent recoil pad will make you smile, its just fun..
Handloaded to its max it ain't fun no more.

Agree - not even close to an issue with factory stuff (at least for me)! Just a whole lotta fun....but it can get expensive. I haven't started reloading 45-70 yet, but I got all the stuff...

My Marlin GBL w/18.5" bbl using Hornady LeveRevolution 325gr ammo isn't bad. It's more of a push than a punch.

the 45-70 recoil to me is more like a shotgun, more of a push than the hard punch of some high speed centerfire rifles. With loads that approximate the black powder loads it is more of a shove still fairly strong but not painful. Go up a step in power level it starts gettign your attention, load it like it can be for strong actions and it will get your attention real quick. Compaired to say a 12ga shotgun, BP equilivent loads say a 2 3/4 inch field load. next up a 3 inch mag then load it to max for strong actions 3.5inch mag.

As kmon says, in factory form it most closely compares to a 12 gauge shotgun whump of a shove.
But even at that just as a 12 gauge even with 3" mags is no problem standing or even sitting like you would often do shooting coyotes or turkeys.
But sit your butt down behind a bench and lean into it and that same shotgun will thump instead of whump..
And if you have the gun for it and get heavy handed with the powder it can make for a short range session.
Basically think of it as a 12 gauge recoil on the light end and approaching real close to 458 WIN MAG butt whuppin recoil on the other end.

You can check out recoil of various calibers to compare it with in Chuck Hawkes Recoil Table online. I love the 45-70.

What would it be coming out of say the Navy Arms Enfield bolt action if any of y'all have shot that weapon.

Shooting the 1885 High Wall it is a very managable recoil, but the action is capable of handling loads that lose the fun rapidly. Also like any other big bore rifle, it depends on the technique.

I shoot a CVA Optima Elite for our primitive weapon season, and I think it's a blast to shoot. Longer shoving recoil rather than a sharp jolt.

To put it in terms that might be easier to understand, you can load it from anywhere from a light to medium 12 gauge all the way up to and past 2x the recoil of a 30-06.

I am running 350 Hornadays at 1900 FPS in a Marlin. I stopped there because it got too brutal for me (not hot). Bad ju ju on hogs though!

I stopped at the same place 1900, figure that is plenty for anything in Texas.

Between a 12 gauge and light 10 gauge. Rifle weight, stock dimensions, and individuals sesitivity can alter perspective.

I've pushed the 300 grains a tic over 2400, that's where it started getting uncomfortable. I settled on around 2200 with the 300 grain HP for an everyday shooter.
That's in the Winchester 1885 High Wall

http://www.chuckhawks.com/recoil_table.htm

-Mickey