I own a couple of 1886 Winchesters in .33 WCF and load for them as factory ammunition is rare as collector's boxes.
The 338 Hornady FP is rarer than their .348 200 gr. Both are 200 gr bullets.
The nickel steel 1886 barrels and actions are tough, but these are 100 year old rifles that still do not use the
Winchester proof steel of 75 years ago. I limit my 33 WCF loading to about 2000-2100 FPS though the 86 can be pushed to 2400.

The best answer for the Model 71 in 348 is to probably order premium bullets from Hawk or Barnes-Swift for hunting. Possibly cast
lead without gas checks for fire-forming or practice with reduced loads.

Any re-bore will require new RCBS dies and the cost of the re-chamber and re-boring. Then there is the value
lost for re-sale > If its a 348 AI or 450 Alaskan, no problem: a 35 wildcat is another story.

"The credit belongs to the man who is actually in the arena-not the critic"-T. Roosevelt
There are no atheists in fox holes or in the open doors of a para's aircraft.....