Very interesting post by redgoat on Remington 870 Forum:
This is more of a “here’s what I’ve observed” post than a how-to or an open ended question.
While researching all of the parts involved in the “flexi-tab conversion” for an older Wingmaster I learned that there is more involved than just switching the shell carrier to the new flexi-tab one. As I understand now, there can be up to four parts involved. I’ve listed them below along with their corresponding parts diagram number
1. The flex-tab shell carrier (part # 7)
2. The newer breech bolt with relief cut (part #4)
3. The newer slide assembly (part number 57)
4. The forend tube assembly (part # 28) (I believe that this is optional, but probably a good thing to include if making the conversion. However, note that a flexi-tab forend tube assembly will not work with the pre- flexi-tab breech bolt and slide assembly without modifying one of the slide rails on the tube assembly. I will post some pics which show why this is so).
I found that the various 870s that I have access to cover a surprising number of variations in these parts and so I have prepared a series of photos to document what I observed.
To get things started, here are some side-by-side photos of the variations I have noted.
Bolt / carrier #1 is from an old well preserved Wingmaster that had a 28″ fixed choke (modified) ribbed barrel.
Bolt / carrier #2 is from an _old_ 870 that appears to have been used by an LE organization. It is a Wingmaster, not a Police model, however.
Bolt / carrier #3 is from a recent Police Magnum model which apparently came with the flex-tab conversion.
Bolt / carrier #4 is from a new (2015) 870 Express, added for comparison, a “flex-tab conversion baseline”.
Visit forum for more information: Evolution of the Remington 870 breech bolt and slide assembly