I did the same thing with my encore. I sent it out and got it cut down to 18", talk about a hard kicker. With the 18" barrel and the synthetic stock my encore weighed less than 6lbs. I had to put a laminated stock on it to keep it manageable off.

how about an old classic wildcat. i did one from a 45-70 to 450 alaskan. it gets your attention when you touch the trigger

577/450 3" Nitro Express. That is about as big as you can go with a Ruger No1 in .458 bore.

ASS_CLOWN

Would depend on how bad you want to punish yourself, mine is a converted 45-70 model and its in 450 3 1/4" NE, with BP equal loads its a lot of fun, but once you get into the NE range its not for the faint hearted

M1, you can do all the old Sharps rounds, and the 458 RCBS, by simply lengthening the chamber of your 45-70 Ruger No1. I have a 458 RCBS re-chambered from a 45-70, and with 480 gr bullets, it is a little vicious even with a decelarator pad. The above cartridges do not require any ejector, or opening of the loading port to do, and can be re-chamered easily! If you want to go the 450NE 3 1/4", or any of the old NE flanged rounds in the .450 bore you need a Ruger No1 H tropicle chambered for 458 win mag. The 450#2NE cannot be done on rifles above a certain sereal number, because the screw holes for the quarter rib were drilled too deep. The 450#2NE chamber is too large out where the front screw hole is. Also with the NE rounds, the ejector, and new rim diameter opening is needed, so the work is more complex. The stock on the No1 45-70 is prone to crack if the recoil gets to heavy, and the tropicle is better suited to heavy recoil.

By the way I did my first night in the army in Fort Bliss, housed in the old cavelry barracs where the gravel field across from the ELP airport is today. And I lived in ELP for 35 yrs. My Mother, and one sister still live there, in the old sandbox!

Since I know you are going to go shoot a Buffalo, then a 458 Lott or 458 Win. would do well, but would probably require settting the barrel back some...The 450 #2 is a good option and if recoil is a problem load it down to 2000 FPS...

I wouldn't mess with all those old Win. calibers, they have nothing to offer on the bad boys of Africa...

Option 2 is to just rebarrel it to a nice 450-400-3" and thats a gun you would cherish from now on...

Heed MacD37 and Ray A on this one. Stick to a lengthened 45-70 sized case head or rebarrel and take your pick up to .577 NE case head and a lot more work.

Some of those Ruger No. 1 quarter rib mounting screws and studs are drilled to less than 0.250" from the chamber or rifling of the bore. watch out for that.

I did a 500 A-Square on a Ruger No.1, but it was a rebarrel and the scope mount (Badger picatinny rail) was placed on a 6" long cylindrical barrel shank (custom profile) before the taper began. This was done with 4 shallow screw holes (3 or 4 threads engaged)(8x40) and soldered too.

You guys have given me some very good ideas and advice (as usual) I am thinking that it may be best to rebarrel and maybe use NECG quarter rib and front sights. That would solve the issue of the screw holes. It is too bad that they drilled them that way. If I went with the rebarrel I could go with a heavier barrel profile to help tame the beast some.

For another opinion, how about the .458 Express? I can't find much data on it, but it's peaking my interest.