**mine was the ball detent model cap all metal no synthetic parts
a lesser grade “synthetic magazine spring retainer” lock down as used on the Express system. Thanks again for the post.REMINGTON SHOTGUN SERIAL NUMBER STRUCTURE (This has nothing to do with the barrel code & the barrel code has nothing to do with the serial numbers) Model 870 LETTER PREFIX 1950 TO APPROX 1968: NO SERIAL NUMBER PREFIX 1968 TO PRESENT: LETTERS USED (IN SEQUENCE) S-68, T-74, V-78, W-84, X-90, A-91, B-94, C-97, D-01, AB-05. The Police shotgun barrel is locked down with a “ball detent” system in conjunction with the magazine cap vs.The Express model utilizes a synthetic trigger housing while the Police models use a compressed metal housing.The Express model has a BEAD BLAST BLUE finish while the Police models utilize either High Luster bluing or Parkerization.Check the serial numbers located on the left side of the barrel on your Remington shotgun. This decoder works for all Remington firearms which have two-letter code on their barrel. ** i assume they mean the dimples ? mine has none - like the police model Remington 700 or 1100 serial numbers can be decoded the same way as Remington 870 serial numbers. The Express model will not allow for the addition of an extension tube without physical modification to the tube and barrel, which can nullify the warranty.If the Model 870 were introduced today, it would be hailed as a major advance in pump-action shotgun design - the ultimate in strength, durability, silky-smooth bind-free action, and sleek classical lines. I must have an odd ball here - maybe one of the first off the line or a mis-marked reciever because as i research the police models i find these differences as well : BUILT EXACTLY LIKE NO OTHER SHOTGUN EVER. I was under the impression that all Expresses had polymer ones, but perhaps the real early guns had the older-style part. I would be interested to know if that trigger plate is the original part.