Tim,,, just because that old gal still feels a little stiff does not mean it hasn't seen a few rounds,, they are made just that good and fit that well!!!
I have a Browning Citori that I bought new in 74-75,, it is a field grade gun,,and it has 3" chambers. I have hunted rabbit, turkey,quail,grouse,pheasant,fox,,,,,,I don't know how many thousand rounds went through it on the skeet range,,,or how many thousand rounds have been through it on the sporting clays field,, and some on the trap field too,, I have used it for just about everything you can think of if it is shot related,,, and if you hold the stock under your arm and just unlatch the barrels they will still to this day and all the rounds down range NOT fall open to the stop,,in fact about 1/2 way open
So the point is,, IF they are taken care of and the hinge pin is cleaned and greased,, or kept lubricated,,,they will last through several generations
You should keep this old gal,,just the way she is,,the blue wear and markes in the stock and forearm are her history,, you said it had sentimental value,,well take her out and enjoy it,,,it will handle any 2 3/4 lead shot load out there,,and when you are shooting this old gal and she is showing you her STUFF,,think of the person that had it or enjoyed it before you,,, that my friend is worth more than the dollar value of this old browning
You have acquired a fine old shot gun,,,,Shoot it,,,that's what JMB intended
that's my .02
ocharry