Looks as though your sporterized 91 had the barrel cut, new front sight, the front of the stock cut back and the handguard discarded and then sanded down to remove the "wire grooves".
You wont find a much smoother action. Its right there with the 30/40 krag. As with the krag, when reloading, care must be taken not to load them hot for the same reason.
I still have one in original configuration. One I sporterized and gave to my cousin. The other, I installed a tapered octogon barrel on and dressed it in a Richards stock in carlo walnut with MC rollover, timmeny trigger, and topped with a Bushnell 3-9x40 A/O. I gave it to his wife for her birthday. Boy was he upset. Oh well, at least they can use the same ammo.
No such thing as a stupid question. What is stupid is not asking it.