M12 barrel

RBHarter

West Central AR
Long ago my Dad and I talked about his having done a couple refits and the ins and outs .......... Dad's gone now and that was a long time ago .
Now I have a 1924 that has a ring right at the magazine hanger and at some point the bead was either replaced and cut through or when the Full choke was lapped out to Imp cyl ........well you can see .
I scored a NOS barrel assy complete with barrel extension . It should be as simple as moving the mag tube and slide and a simple <15° set screw adjustment with a possible breach face lap .....

Has anyone done this ? Any pearls or pitfalls ?
 
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fiver

Well-Known Member
I bet it's more like a drop in fit with some very minor wiggle and jiggle type fitting.
I have swapped triggers, fore-arms, butt stocks, barrels, and bolt slides around on a lot of 120-1200, and 1300's just messing around, and all of them have pretty much just replaced the other part.

the one thing I would look at is the bolt lugs fitment to the new barrel.
 

Winelover

North Central Arkansas
Fifty years ago, I purchased a used but minty M12 from a Jeweler. Was my first firearm, I was 17 years old. Dad had to make the purchase for me, since I was underage, per Michigan law. Paid $75 for it and came in a hard leather "Leg of Mutton" case.

The numbers matched barrel came with a "Poly Choke", which I didn't care for. Especially, inaccurate when shooting foster type slugs, for deer hunting. Found a new barrel at Numrich Arms and had a local gunsmith install it. I had it cut down to riot length/cylinder bore..............making it more handy and more pleasing to the eye. Resides that way, in my safe, to date. Kept the original barrel, in case I ever wanted return it to the condition I purchased it in.
 
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RBHarter

West Central AR
I took a long look last night . The headspace ring is inside the action , kind of like the K98 only it is adjustable , the lights started coming one a little . Like the 3-4 bolt heads of the Enfield the M12 had 4 rings to take up wear inside the action . The take down has the interrupted thread arrangement which allows for clocking the take down fit and presumably , the lights are still pretty dim , the breach face to headspace ring fit . The tilting bolt and adjustable Mauseresk double ring breach is genius . The interrupted thread timing adjustment looks to be pretty straight forward as well . Being of the mechanical sort this is just about the place where confidence in understanding and reality collide and either slip into place or explode like a dozen tape measures out of their cases in LFRB (USPS humor , boing thlick thlick thlick etc .) .
 

RBHarter

West Central AR
The BPS has the tilting lug that hooks to a barrel tang extension like the M500 etc that is a no brainier swap the M12 doesn't actually have bolt barrel contact . The bolt tips into a notch in the receiver at a fixed point . The head space ring is moveable within the receiver a heavy brass case or steel case could be fired without the barrel in place , of course it'd be hell to get it back out , but it could be done in a moment of diress . When the mail gets here I'll take some pictures .
 

Gary

SE Kansas
My all time favorite shotgun, I have 5 of them with the oldest being a 1925 model. Interestingly, when I stripped the wood off the action I found a 1925 hunting license under the butt pad rolled up in the drilled hole for the attachment bolt.
 

RBHarter

West Central AR
Couple of the old parts .
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Inside the action there are 2 locking screws on the headspace ring .
The bolt and rim butt up to that with 2 extractors . The other side of the the barrel has a ring that butts up to the headspace ring via the set screw wedge and notch arrangement of the extension .
 

RBHarter

West Central AR
My all time favorite shotgun, I have 5 of them with the oldest being a 1925 model. Interestingly, when I stripped the wood off the action I found a 1925 hunting license under the butt pad rolled up in the drilled hole for the attachment bolt.
I only have 4 . I kick myself every time I look them over because of the mostly blind shop owner that had a 50s vintage trap marked as field grade price . Polished wood , 2 bead rib , 28" , jewled bolt , trigger and elevator ........ Oh well .
I have a 1916 , this 1924 , Dad's 1940 and Mom's 1968 , well you know when she's done with it . As expected the one owners are in the best shape with this one having been rode hard . Dad actually got his in 57' as new . Mom's was a factory direct to the dealer "use up the parts" gun in 1968 just under the wire or maybe the book was lost in a fire .......
The 1916 is the smoothest and best polished of the bunch but shows its age in a way that a well loved gun will . I suspect it was probably a Christmas goose kind of gun until the late 80s maybe sooner and sold/pawned by an inheriter . Sad but I guess eventually it happens to it all .
 

Gary

SE Kansas
Now that is pretty interesting!
Could you still read whose it was?
Absolutely, totally legible. What's doubly interesting, the license was issued in my home birth town. I bought the gun from a fellow that lives several counties removed from my birth town.
 

Eutectic

Active Member
Fitting another barrel or even another 'front-end' to a Model 12 is quite a complex project done correctly! I've coached others on the Model 12 and have done several Model 97's. They are basically designed the same with the 12 copying the 97's take down fits.
Sometimes another 'front-end' or even barrel with extension piece on it will fit and headspace OK...and be adjustable for slop. Close enough to work??? But not the way I work! The changing of a Model 12 barrel is a multi-faceted set of fits! And modern man has trouble wrapping their heads around several fits at once; each fit affecting the other fits!

First you'll need a way to check headspace. Go-No go gauges.... I didn't have them for my first time. So I started with my mic on rim thicknesses. !2 gauge hulls can run from .058" to .068" thick with a good majority towards the middle. I found some of my wife's pricing labels. These were .002" thick. 3/4" diameter and sticky on one side. You can ad these one at a time to the hull base closing the empty in the gun and find headspace down to a thousandth figure!
I've got a fired hull with a .063" thick rim and we shoot for .008" to .010" headspace. I say 'we' as a gunsmith friend of mine also likes this method!

So....... this headspace in a model 12 (or 97) is from the face of the breech bolt to the face of the chambering ring with hull in it. The chambering ring inserts into a snug fit in the receiver and is held by a screw(s) on receiver side(s) It becomes part of the chamber when the barrel is in place. They run a fairly uniform thickness of 0.156" but can vary. The thickness and internal fit to hull can affect headspace and modified ones have been used to gain a few thousandths for excessive headspace. Many Model 12's are quite loose in this department when checked. So a new chambering ring is our starting point. You will find the hole in it too small!!! The shell won't go through!! It's that way for fit (one of many) The barrel's chamber you are trying to fit may not be exactly concentric with the barrel threads! S o o after the other fitting is done the chamber ring is reamed! Winchester's process was to put layout blue inside the barrel chamber for an inch or so..... attach barrel to receiver....... insert special piloted chambering reamer through receiver and the install driving rod from muzzle end! Ream till blue was kissed. Correct way.... Winchester's gone.... Maybe a few Model 12 specialists still have the ability?? I have hand fit several chambering rings now and it is quite the test of skill. I recently got a beautiful 1901 manufactured 16 gauge Model 97. It had been shot once after decades as a closet queen. It locked up!..... My gunsmith buddy called me and explained..... "Chambering ring." I told him. Long story short I got the gun. It was full of new Winchester parts! I commented it had (I would give) $250 just for parts! But I fit the chambering ring (finished fitting) and wanted $200 labor for 6 hours work...... The guy choked and my gunsmith buddy tells him I'd give $250 just for the parts.... Now I have the old (and great) gun!

I found a new old stock Winchester Model 97 12ga barrel! What a find! What a pain! The barrels come with the tenon long for fit adjustment...... I had a new extension piece..... So I started here..... The barrel didn't index right so I had to machine the shoulder (an exact amount leaving the bead sight up and a torque fit tight in the extension as well. Did I say I had to make a tool (wrench) to tighten it? The old chambering ring was off eccentric. I installed another. Then I must have sat at the drawing board a week! Multi-faceted fits galore! Winchester made several different take-up rings. I had fit the extension piece face-up to the first one which allowed maybe five future changes to tighten. Then I had to figure forward travel length turned in by thread pitch plus headspace to correctly contact the chambering ring! As said the new barrel tenon was long.... and I had to figure exactly how long before facing.!!

I would much rather fit a barrel to a bolt action rifle any day of the week!!
 

RBHarter

West Central AR
Very insightful ! Thank you !
This barrel is fitted with the fitting and index block . I will have to salvage the rest of the bits and pieces .