It will have to be custom made.
No
Yes
The Browning 2007 Product Catalog states that the A-Boltchambered for 25WSSM with a 22" barrel has a 1 in 10" rate of twist.
If it is a Browning Superposed 12 gauge it was made in 1959.
You will have to contact Browning to find out. If you are referring to the run of Browning model 71's that were made between the mid to late 80's and early 90's, there were a total of 14,000 made. 4,000 Standard Rifles with a 24 inch barrel. 4,000 Standard Carbines with a 20 inch barrel. 3,000 High Grade (Deluxe) Rifles with a 24 inch barrel. 3,000 High Grade (Deluxe) Carbines with a 20 inch barrel.
Requires professional appraisal
100-10000 USD depending on specifics
50-500 uSD
1 in 14
Browning,s home page should contain this info.
It will fit on the frame but the action will not function with 3 inch shells.
Some do, some don't. If the barrel is not marked 3"shells, then no.