early Model 1912 in 20 gauge- Just picked up another M1912- sn is 32074== 25" plain barrel full choke nickel steel field gun in about85% OAL condition- no chamber length marked, as on my other 20 ga. M12- 1931 field gun 28" Mod. choke solid rib barrel and stamped 2&3/4" chamber. I haven't shot it yet, but am guessing it has the 2&1/2" chambering. Would I be safe in shooting a 7/8 ounce skeet load in it- is it true that the main operation to "convert" a 2&1/2" to a 2&3/4" 20 bore pumpgun is the differing radius on the front facing radius of the ejection port, as machined into the steel of the receiver port?? I'd like to shoot it this coming Fall on grouse- carries nicely in hand, and I like the first style "perch bellied" buttstock- 7/8 ounce of No. 8 chilled shot in that Full choke ought to "defeather" a Sir Ruff like downtown--RWTF

As I recall, the 2 1/2" early Model 12 20 gauge guns work reliably with 2 3/4" shells. The 2 1/2" 16s do not work with 2 1/2" shells.

Tough getting a grouse on the wing with a full choke there Foxie. A high percentage shot on one sitting on the ground or in a tree is not so tough with a full choke. I used to hunt grouse with an IC model 12 twenty ga in my younger years. It was a killer. Had a poly-choke rib glued on the barrel. I sadly sold that gun. Went lighter with a Browning super lightning 20 bore. I like it best, but I did like the Model 12.

All my Model 12's and the now Model 1912 20 bore are full choked, except my Pigeon Grade Trap- 1948- milled rib and 30" Imp. Mod. and they all fit me and pattern to point of aim, for me. i like the confidence that only a game bird shedding feathers and crumpling mid-air gives, whether a barn pigeon, crow, or waterfowl. Some of my few doubles have more open chokes- Today I am mainly a pass shooter, like that extra reach a full choked guns gives a gunner.

The early short chambered M12 20ga guns can easily be converted to 2 3/4" ammo.
The chamber is lengthened. Make sure the gunsmith takes the 1/4" length chamber ring inside the frame into account when measuring and cutting the new chamber to 2 3/4" OAL.
The ejection port is lengthen forward approx 1/8" with appropriate radius at the corners. This for ease of rejection of fired 2 3/4" cases.
That's it.
There's no extra parts mods to be done as when converting the FN A5 short chambered 16ga to 2 3/4".

Many will say to leave the early Win M12 20ga guns as original, They are more valuable as orig. Well, how valuable are they?
The other comment often made is that the early short chambered guns are often fired with and have probably fired more 2 3/4" ammo than the short length shell they are chambered for,,and are still in one piece.

2 1/2" length commercially loaded ammo is available if you want to shoot that in the orig length chamber. It's not hard to reload with a standard press either.

The options and facts are there. You make your own decisions.

I don't understand why the poster "Kutter" mentions an expensive rechambering of the 20 gauge Model 12 when I stated that such an expensive alteration is not required to make the gun work. My short chambered 20 gauges work with 2 3/4" shells, and yours should too.

You are most astute Eightbore- I put 20 2&3/4 AA skeet loads through it-worked perfectly, as you advised. great tight patterns too. If I should have thought about having a gunsmith follow Kutter's mantra, I'd think again-the only good gunsmith in my neck of the woods was the late Brad Bachelder.. RWTF

If you measure most American 20 ga hulls after firing they are way closer to 2 5/8 than 2 3/4.

Enjoy your new Model 12.

Kutter-great job answering op question about converting 2-1/2" to 2-3/4" ejection port. Always enjoy your no nonsense post.

The orig Post wondered about the actual conversion process,,I explained what is done for the conversion.

I didn't say it was necessary, I only explained what was done. Not a mantra, just simply what the process is. Nothing more, nothing less.
You mention twice that it's an expensive rechambering/alteration. That's your opinion w/o placing a dollar value on it.
I never mentioned any costs involved and won't price others work. It's not the issue here anyway. The question was how is it done.
You decide if you want it done or not and then if you want to pay the costs.
That's your decision, read the last line in my orig post.


I also stated that many of the early guns have been shot and continue to be shot with 2 3/4" shells in the orig short 20ga chamber.
I never got into the safety issue at all,, if it is or if it isn't. and I will not.
I could care less what others do with their guns.
Again,,It's your decision.

Simple facts on what is done to convert the M12 20ga short chamber to a 2 3/4" .
Take it or leave it.
No judgement on what anyone wants to do with their gun.

I know my model 12 sixteen gauge had to be chamber sleeved (both barrels since it is a two barrel set), and I think the ejector port extended to accommodate 2 and 3/4" shells. My Grandfather's Browning A-5 sixteen ga only had the ejection port extended. If I have any short 20's they all must shoot 2 3/4" shells just fine because I have not done anything to them...Geo