The Model 71/76 superseeded the Model 71/84. In the 71/76, the bore diameter was normal at .437", however the groove diameter was .457" - supposedly to better collect the fouling for longer shooting strings before military accuracy was comprimized. The bullet was a paper patched ,446" bullet, a full .011" smaller than the groove diameter.

Due to being a soft, paper patched bullet loaded with the 77gr. black powder charge, the bullet would obturate to fill the rifling when fired and accuracy was pretty good- for a while. The chamber's neck dimaeter would not allow seating a bullet larger than the normal .446", hense in later years ie: 1900's through to about 1960 in Canada, when CIL/Dominion produced this amo for the civilian market with a paper patched bullet and smokeless powder, the accuracy was horrid - in the earlier rifles. This was because smokeless powder does not hit the base of the bullet quickly enough, too soft a blow, to cause obturation. Thus, the bullet's paper coating would be burnt off in it's trip down the bore and accuracy was horrid.

The model of 71/84, actually had a much better bore- size/wise wit it's .446" groove diameter and this rifle model shot the much later smokeless ammo quite well, usually into 3" at 100 meters with the rifle's issue sights - which were quite good as far as early sights go.

This pictured rifle is a 71/76 9with new ramp front sight installed due to the original being missing.

At the time I was given this rifle, I couldn't obtain Starline brass for it and due to the chamber neck's limitations as to bullet size, I rechambered it for the .450 Alaskan by grinding down the pilot to .437" to fit the bore. It's a great handling little carbine and shoots well due to the 20" twist rate. It's light at only 6 pounds and the 500gr. cast bullets at 1,320fps do kick a bit (BP load). It easily handles smokeless loads with those same 500's running 1,500fps. It's a thunper.
For a gun in good condition with collector value, I'd not suggest this move, except for another 71/76 which wanted to go hunting. In that case, a simply neck/throater to open up the neck would suffice. Brass is available today in the original 11 mm Mauser.