Pretty Custom Winchester Model 12 20 gauge

Buckmastr

Buckmastr

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Picked this one up recently. A well done custom Model 12 20 gauge 25" FC barrel from 1922. Very nice and wanted to share. :dancingbanana:













 
Buckmastr said:
I measured it. You are right. Hmmm.
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Your gun may have had the chamber lengthened during the re finish. If not 2 1/2", chambered Models 12 will run 2 3/4" cartridges without any issues including zero safety issues. The chambers in those guns are slightly long anyways. Enjoy. Remember to include the chamber ring in the receiver when measuring model 12 chambers.

Darryl
 
Thanks Darryl. I measured it with a deep socket and compared it to the same measurement in a known model 12 20g 2 3/4” chamber. It was short. I’m not sure how a 2 3/4 inch shell will feed but will find out soon. Most of what I’ve read says it’s unsafe to shoot a 2 3/4 shell in a 2 1/2 chamber. But I will try it with some light loads.
 
There have been many studies and it is perfectly safe to shoot 2 3/4" shells in a 2 1/2" 20 bore model 12. The belief once was that the case mouth opened into the forcing causing a pressure spike. This has been proven to be untrue. There is a slight increase but your Model 12 is plenty stout enough to handle that and then some. The big issue is the proof of the gun. Short chambered English guns often are not proofed to handle modern North American 2 3/4" 20 bore cartridges. Even the lights loads you intend to use will be at or over 9000 psi very little less than a standard 20 bore hunting cartridge. Check out double gun shop dot com search out the thread on short chambers it is very eye opening and interesting. The short chambered Model 12 20 bore I had ran 2 3/4" cartridges with no issues.


Darryl
 
That all being said about the 2.5 or 2.75 you can buy the 2.5" not that hard to find .I have a 1913 20g ,not quite that nice and have run both through it. I will say the 2.75 do not pattern as well but that could be just the shell that I was using. I have found huge differences in the brands especially in the last 5 years. still a beautiful piece.. RD
 
madtrapper143 said:
There have been many studies and it is perfectly safe to shoot 2 3/4" shells in a 2 1/2" 20 bore model 12. The belief once was that the case mouth opened into the forcing causing a pressure spike. This has been proven to be untrue. There is a slight increase but your Model 12 is plenty stout enough to handle that and then some. The big issue is the proof of the gun. Short chambered English guns often are not proofed to handle modern North American 2 3/4" 20 bore cartridges. Even the lights loads you intend to use will be at or over 9000 psi very little less than a standard 20 bore hunting cartridge. Check out double gun shop dot com search out the thread on short chambers it is very eye opening and interesting. The short chambered Model 12 20 bore I had ran 2 3/4" cartridges with no issues.


Darryl
Click to expand...

The work that has been done of shooting 2 3/4" shells out of 2 1/2" chambers suggests that the spike in pressure due the the cartridge opening into the forcing cone is around 500 to 750 psi with 12 gauge and progressively higher as the gauge size drops. Thus, when shooting a vintage 12 gauge, if I have determined a pressure max of 8000 psi is fine, and it has 2 1/2" chambers, then shooting a 2 3/4" shell generating 7000 psi is just fine.

I don't know the 20 gauge numbers off the top of my head but the salient points are...arrive at what you consider to be the safe maximum pressure and stay under that. It doesn't matter if you stay under it by shooting a 2 1/2" shell that keeps the pressure down or a lower pressure 2 3/4" shell whose pressure rating, when combined with the 20 gauge spike from the longer cartridge, stays under your maximum pressure level.
 
Thanks everyone for your feedback. I’m surprised that it wasn’t chambered for 2 3/4” shells when all the work was done to it. But it sounds like it doesn’t really matter.

Grouse man, the gun is reblued, restocked and ribbed sometime between when it was built and now.
 
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