Thanks for the kind words, Mitch & Roger.
All it takes to clean the old stuff off the metal is lots of elbow grease, white vinegar, and mineral spirits. If these were "collector grade" guns I wouldn't use much more than the mineral spirits on the metal, because vinegar strips the finish off right quick (relatively speaking) so with my wartime German rifles I avoided the vinegar.
Also, my intention is to refinish these guns completely, so I must also do some 220/320/400 grit sanding with some components as well. At the moment I'm on the fence regarding what finish I am going to use on the 520. Same goes for the Model 8. Seeing the guns reassembled "in the white" reminds me of the old stainless steel Mossberg Mariner shotguns. I'm actually considering parkerizing believe it or not. Even Cerakote finishes. Besides classic deep black/brown Belgian rust blue.
Roger, I meant to add something to a comment you had made much earlier regarding how your son's Model 520 I believe had a tendency to drop loose shells if the gun was held at a certain angle. Like if the lifter spring wasn't working right, or it was placed incorrectly in relation to the lifter, it can make that occur. I found that out in my working with these 520 shotgun parts - one receiver was missing a few parts, specifically a lifter spring, which when fitted incorrectly in relation to the lifter arm causes it to not "snap" back to battery position at all.
So maybe, the problem with shells dropping out of your shotgun is related to the lifter spring placement.
Check out these pics of the 520/520A/620 schematics - specifically, parts 520-121 and 520A-132. The lifter and lifter spring.
Sorry I can't show any of my own gun assembly pics at the moment, haven't taken 'em yet!
Adam
I am a regular joe, consisting of 78% coffee, 12% hot air, 9% organizational abilities, and 1% luck.