I just got a Remington 870 wingmaster at a gun show for 140 dollars but it needs a couple of parts. It's a 12 gauge in very good condition and was used very little. I need to get a new firing pin spring and a locking block. I don't really know what locking block to get rhouht because I've read that there's some old style bolts and online I've seen over sized locking blocks and don't know what to get. It's just a regular wingmaster that was made in 1974 and only shoots the 2.75 inch shells. I'd appreciate any help on what locking block to buy.