16 ga. Win. Mod 12

jds56jds56 Member Posts: 22 ✭✭
edited September 2008 in Ask the Experts
Is there a way I can measure the correct chamber length of this shotgun? I bought this gun in the early 60's in a pawn shop in near new condition, SN.3600xx and have since fired several thousand rounds of off the shelf 2-3/4" shells with no problems. All have cycled thru the magazine and the fired hulls look normal, to me anyway. The little gun is still as tight and slick as ever. The barrel is stamped "NICKEL STEEL MOD 12-16GA MOD"

From reading this forum and others, it was made in 1924 for a 2-9/16" shell. I had no idea such a thing existed. Is 3/16" difference in shell length significant? An American Rifleman article implied that some of these vintage shotguns were chambered for 2-3/4" shells.

I want to pass this gun on but not if risky using modern 2-3/4" shells. Thank you for your advice.


  • Bert H.Bert H. Member, Moderator Posts: 11,274 ******
    edited November -1
    Hello jds56,

    If the gun is not marked "2-3/4" on the barrel (or possibly on the bottom of the receiver just below the serial number), it was originally manufactured with a 2-9/16" chamber. There is also the possibilty that a previous owner had it opened up for the longer shells after-market (which I suspect because you are not having problems ejecting the empties). Any decent gunsmith should be able to verify the chamber length for you.
  • Wehrmacht_45Wehrmacht_45 Member Posts: 3,377
    edited November -1
    If you are not having trouble ejecting the empties, then it most likely has been lengthened to the standard 2 3/4 chamber. I have an old Stevens 520 that had to be opened up according to its previous owner.
  • bobskibobski Member Posts: 17,868 ✭✭✭
    edited November -1
    it is dangerous to shoot 2 3/4 hulls in 2 9/16 chambers. youll have the tip of the hull blow off from it hanging past the forcing cone. and, if it jams with the wad as it fires, the gun will blow up in your face.
    Retired Naval Aviation
    Former Member U.S. Navy Shooting Team
    Former NSSA All American
    Navy Distinguished Pistol Shot
    MO, CT, VA.
  • Old GunnyOld Gunny Member Posts: 193 ✭✭✭
    edited November -1
    Also you can check the radius (radi?) on the front of the ejection port opening- the early Model 1912's and M12's with the nickel steel barrels and the shorter than 2 & 3/4" chambers; 2 & 1/2" for the 20 gauge and 2 & 9/16" for the 16 gauge had a 1/4" radius at top and bottom- when in 1927-28 they went to a std. of 2 & 3/4" chambers for the 20 and 16 gauges, they lengthened the ejection port slightly and increased the raduis (radi?) to a 3/16" takes a fine eye for M12 detail to see it-many had the 2 & 3/4" stamped on the magazine tube extension next to the serial numbers-yours will also have the older "perch belly" style buttstock with a smaller diameter pg- after 1935 they changed the buttstock and went to a fuller pg-I have chamber gauges- a "field fix" is to remove the barrel/forearm group from the receiver, roll a postcard to the exact diameter of the barrel I.D. at the breech- slide it in slowly until you feel it catch- what we call "sticky-tight" with a micrometer-and at that point make a pencil "witness" mark flush with the threaded barrel extension on the postcard- remove and measure- that's your aprox. chamber length- Oh, make sure the barrel is 100% clean and free from oil or any "nerdlingers" first to get a true reading. I have 10 older Peters purple paper 16 gauge shells 1 0z. field loads of No. 6-and I don't own a 16 any more-I had a 16 Model 12 (is there any other Repeater quite the same quality? NO__) and as I hunt geese more than I do quail, I traded it against a M12 3" Heavy Duck- I love it, the geese, I am afraid, most likely don't. O.G.
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