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Discussion Starter · #1 ·
By friends dad bought a weird one.....12ga, 32" full choke, solid rib barrel with 2 1/2" chamber. He found out about the short chamber the hard way....extraction problem with 2 3/4" trap loads. Barrel isn't stamped with shell length either.Yikes.

It has no apparent damage from the wrong ammo. It doesn't have any european proof house marks on it either.

How strange is it? It's had at least one refinish so it's not in originial condition. He was asking me if he should hang on to it.
 

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12 ga. Model 12s did not have 2 1/2" chambers. They were 2 3/4".
Extraction problem had nothing to do with the chamber length.
More likely a dirty chamber or worn extractor or the brand of ammo(some give problems at times).
How did you measure the chamber?

32" solid rib??? Yeah, I would hang on to it!
 

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OK. But you didn't answer the question.

Restated: did the person who measured the chamber take the receiver ring into account?

I mean no disrespect, but this is an extremely common error.

I used to be surprised to find an otherwise competent gunsmith who did not understand this aspect of M-12 design - I have been disabused of this notion through years of experience.

Sam
 

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Discussion Starter · #8 ·
Quick ******* method.....

Couldn't drop a 3" shell completely into the chamber w/ barrel on receiver......if it was 2 3/4" it should go in. I didn't try to close the bolt on it for obvious reasons. Figured it could be short chambered on ******* test.

Verfied by gunsmith afterward....he ws told about extraction trouble......but not my check.
 

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Going back now to your original post, I'm wondering why extraction of 2 3/4" shells would be problematic. Are empties sticking so that you can feel resistance when you knock those 2 3/4" trapload empties out with a rod? Or is the extractor broken or worn?

Short chambered 20 and 16 ga M-12s will extract 2 3/4" shells all day - the problem is ejection. Empties hang up in the gun because the ejection port is slightly shorter than needed for 2 3/4" empties. Is this what you meant by difficult extraction of 2 3/4" trapload empties?

If possible, can you take the gun down and measure from end of barrel extension to start of forcing cone. Before doing this, check to see if there's a ring of crud built up near the forcing cone. If there's buildup out there remove it with solvent, brush, and elbow grease - then measure.

You also mention the gun's been refinished. Is the barrel a Winchester stamped factory barrel? Does the SN on barrel extension match that of the frame?

Sam
 

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Discussion Starter · #11 ·
Chamber & barrel are clean, Winchester factory barrel with matching numbers to frame. Extractor is in good shape. The extractor was my first suspicion. The extractor didn't slip off the fired shell though, so the grip was good. It was stiffer than normal to try and get open with resized light reloads and factory ammo....no steel heads either. Remington STS & Win AA. He shot several rounds of trap with it before it really started getting bad......Most likely the heat and buildup made it worse. Ejection was OK once it was opened.

Don't roll your eyes at me cowboy......I don't have gauges so I have to make due with what I had on hand. And be careful saying that something dosen't exist.

I'll drop the subject. Just though the forum would be interested in a strange variation. I've seen enough firearm variations that weren't supposed to exist to think this one might be special. 12ga, 32" solid rib, fancy wood, and 2 1/2" chamber. Only reference I have in my library is that 2 3/4" became standard for the M12 in 12, 16, & 20 gauges after 1930 (pg. 57 "Winchester Shotguns & Shotshells" by Ronald Stadt) The S/N dated the gun to the early 20's.
 

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"Don't roll your eyes at me cowboy......I don't have gauges so I have to make due with what I had on hand. And be careful saying that something dosen't exist."

Don't take it personal Seaark . Cowboy is most likley the only person that has never used a dime to a quick check on a choke .
 

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Seaark1660 said:
It was stiffer than normal to try and get open with resized light reloads and factory ammo....no steel heads either. Remington STS & Win AA.

Ejection was OK once it was opened.
Don't give up yet. The symptoms you describe so far don't have much to do with a short chamber. One more try, you can do this without a gauge: action open, insert your finger (yes, your finger can detect a few thousandth - we do it all the time with primer depth checks). Feel the junction between chamber ring and the chamber portion of the barrel. Is there any chance that the diameter at the ring is slightly less than the diameter in the chamber just beyond? Take a look at a fired hull. Is there even a smidge of a shelf on the brass that suggests that the ring is narrower than the rest of the chamber? If there's no discrepancy in diameters, is there perhaps a burr, or some roughness to the proximal chamber or ring?

Sam
 

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After reading your posts, I also would highly suspect the chamber ring. Had a M97 that had similar problems with extraction of spent shells. Just like Sam mentioned, the chamber ring was a tad undersized than the chamber. It doesn't take much. The brass expands more in the chamber than inside the chamber ring, preventing the shell from extracting past the chamber ring.

Sometimes you can see or feel a ridge, on the brass portion of the shell, a 1/4 inch from the rim.

I fixed the M97 by opening up the chamber ring a very, very small amount until no ridge was felt when I ran my finger along the inside where the chamber ring meets the chamber.

BTW, if you take down the barrel half and measure the chamber it will be 2 1/2" plus 1/4" for the thickness of the chamber ring that remains inside the receiver, adding up to a 2 3/4" chamber. Even the preceeding Model 97 came with 2 3/4" chambers. It was the earlier Model 1893 that had 2 1/2" chambers.

If the M12 you're describing has the original front half, and serial numbers to the receiver, and has not been monkeyed with; it came from the factory with 2 3/4" chambers. The only other option, in 12 ga, was the heavy Duck with 3" chambers.

Regards:
Rod
 
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