doublegunshop.com - home Forums Thread Like Summary - older M1912 20 ga.

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

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.

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.