doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 12 ga. Heading Gage

Is anyone familiar with this or does anyone have one. It is for opening up the front end of a shotguns chamber to allow the shell head to fit. The diameter is .890 with a 55 degree taper for the leading edge.

I bought a set of barrels and they needed to be fit. The dimensions of my old barrels third bite and this barrels bite are the same. Distance was different from end of breech to hinge pin on new barrels. Had to file .025 from breech to make barrels fit and now have to make this area where shell fits deeper to accept shell and let ejectors fit when closing gun.

This is the term I found in an L.C. Smith book and it gives dimensions for both a hand tool and a machine tool.

In order to keep tool straight a pilot would have to be made for chamber size.

I think Manson or Clymer will make a reamer that not only cuts rim recesses, but forcing cones and also has a replaceable pilot. A friend has one that has been used to cut out the undersized rim recesses on 28 gauge Parkers, at the same time cutting the chambers a little longer than the factory cut 2 3/8". This can't be an inexpensive tool, but it has been used several times, will last forever if cared for, and is easily worked by hand. I used it on two 28 gauges, taking less than fifteen minutes to do both, outdoors on a picnic table. I have cut rim recesses on a Parker 28 gauge with a right angle attachment on a Bridgeport, but would never have attempted that if I knew such a hand reamer were available. At the time I used the Bridgeport for this job, almost fifty years ago, I would guess that such a reamer probably was not available.

Brownells has them, $160. Chamber reamer with a pilot. Cleans up or lengthens the chamber and cuts the rim recess. I have one and have used it for several years to lengthen chambers to 2-3/4".

Bill and Jim, in looking at a few online catalogs, Midway didn't seem to carry this type of tool for shotguns. They had them for pistols and rifles, I believe, but not for shotguns.
Brownell's has something that I think might be it. It doesn't give the O.D. of the reamer but it has the 55 degree angle and it does have a pilot.
I'm guessing they don't give the O.D. because of all 12 ga. shell head being the same. I wish they would give it for the chamber size because I would think you would want that to be very close.
Again, I think this might be it.

http://www.brownells.com/.aspx/pid=5164/Product/SHOTGUN_RIM_CUTTER___HEADSPACE_RING#

I have one of these tools. It measures .890 outside diameter, so it should work for you. Bill

I don't think that is what you want. That tool is for use whan the rim cut is too deep. It cuts an oversize ring and then you solder a sleeve in and then re-cut the rim area as needed. You should get a chamber reamer. You've shortened the barrels so your chamber is a bit shorter, as well. Page 419 of catalog #62.

As I understood David's original question he is referring to a tool for cutting the rim seat, nothing more, nothing less. This tool is pictured & dimensioned in the L C Smith Plans & Specifications book which I presume is what he was referring to. It cut no other portion of the chamber & was called a Heading Tool. I do not know if anyone offers these independly of the entire chambering reamer currently or not. Any good toolmaker could of course grind you one, but it would not be in-expensive.

The one that Jim Legg recommends ($160) is the one I used. It does it all and is worth the money. Maybe someone would lend you one. That's how I got mine.

Miller, that is the only thing I could compare and explain what I had to do, and yes it would be for the head (rim)of the shell. That dimension has to be a standard size, I believe .075-.080 deep. The "rims" I have measured were .072-.074. Using a depth mike I found the shell to be .005-.008 recessed.

The "land" between the ejectors has to be machined out also, not so big a deal using a 3/8" end mill, the hardest part will be to index and clamp it.

Jim,
I wasn't sure what they were referring to. You explained it a lot better than me looking at it and figuring what the ring was for. What made me think it was the right tool was the 55 degree chamfer for the rim.
I'm guessing this then would cut it oversize to allow the ring to fit the chamber, and then like you said, re-cut the ring to the correct depth.

I don't have catalog #62, but looked up under reamers. Is this the one you were talking about, 184-052-729 $160.00. This reamer is for bore size .729, and I didn't see any for .890, rim size.


Bill Meyer, is your tool like the Brownell one? If so than the .890 O.D. would be the right size. Does it have a pilot to follow the chamber and what size is that.

You guys are great with information and knowledge.

If it is like the combo piloted reamer I used for the 28 gauge, only the pilot dimension is mentioned in the description, the rim recess and chamber/forcing cone dimensions are understood to be standard. The only instructions needed are "Don't go too deep at the rim recess." All other depth dimensions are non critical.