Gun shop, gun shows, pawn shops, on line auctions, want ad, for sale ad, estate sale, garage sale, etc..
I would start my search at Smith and Wesson first.
Try CDNN, Samco, SOG, etc.
You buy a book that has the serial numbers in it.
gun shop, gun show, pawn shop, for sale ad.
You will need to buy or find a copy of the Standard Catalog of Smith and Wesson.
Try gun shops, gun shows, pawn shops, estate sales, garage sales, for sale ads.
Mossberg 1000 barrels will fit the Smith & Wesson 1000 Super 12 only !!
You will have to buy a book.
1973-74. Supica and Nahaus' Standard Catalog of Smith and Wesson is worth it's weight in gold (and it is very heavy) to anyone who thinks they may ever buy a S&W. also have serial numbers...
Call S&W and they will tell you. Buy the Standard Catalog of Smith and Wesson, 3rd ed by Supica and Nahas and look it up.
Try e-gunparts.com
suggest you buy a copy of the 'blue book' on gun prices (book store) and look up the model 60