Got Savage 220A .410 very difficult to open from passed family member stored in closet for decades. Gun marked Chicopee Falls, Mass April, 1954 with matching inspector marks.
I removed buttstock, forend and barrel and brushed/soaked receiver and firing mechanism with CLP. The locking bolt is uncentered touching left side of receiver. When Moved with thumb it frees up and will move with top snap. But when top snap is released the locking bolt hangs up again.
I removed locking bolt. Width measures .607 at bottom, .610 where pin goes through. Length measures 1.570 from top where it engages top snap to bottom. Depth measures .418 from front flat to rear. Pin through locking block and receiver is tight.
I put the locking bolt back in and it centered in receiver and moved with top snap. But when top snap released the locking bolt arm disengages from the snap arm. I can move it forward to reengage but when release top snap it disengages again.
Could the locking bolt arm be too short? Could it be the top snap arm? I stopped disassembly at removing locking bolt. So I didn't inspect top snap arm.