They don't call 'em the Finest repeating shotgun ever made in USA for nothing-I own 7, all pre-1952, most pre-1940 and 80% are 12 gauges (including the 3" Magnums)--I grew up with them, as a MOS 2112 in the USMC, worked on many, plus the M25 and a few assorted M1897's--BUT- there is always something new to learn-- here's my experience, hope it might help someone--
My "oldest" is now a M12 12 gauge field grade 28" full sn 264437-- Nickel steel, but not a M 1912-- made aprox 1921--I bought it last Nov. from a "Mom and Pop" shop near to the farm where I deer hunt (and where I also bought the BSA .22LR Martini 12/15 heavy Target rifle)-- Lotsa wear, shortened butt (cured with a slip-over pad) but clean, swet shucking-- Shot it at our Club for some Winter Tower pheasants, killed many crows and barn pigeons too- BUT--
About 2 months ago, I noticed that the shell carrier was "sticking" when in the lowered position, when I went to reload the magazine- did a complete strip and clean (again- did that right after I bought it too) and ordered a new piano wire pivot spring from Brownell's- still had the occasional problem--
I "lived with it" by pushing the carrier with the tip of a knife blade- and it would feed and cycle the shells from the magazine A-OK- after I repositioned the carrier to the "Lock and Load" position--
The culprit- went to my Madis book page 173-- item 10- carrier does not rise- binding plunger- remover pivot machine screw NOTE- this is a LH thread- counter-rotational, like the threads on the shaft of a circular saw, etc)-- removed spring (again) and checker carrier and milled sides of trigger housing for burrs, crud- clean as a whistle- BUT- the head of the through pin- actually the hammer axle pin-- was protruding about 1/32" (eyeball guess) above the surface of the milled flat- I tapped it flush with a punch, and-- PROBLEM SOLVED--
