doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Conversion - SxS Hammer gun to Cap or Flint ML ??

Yes, I actually didn't realize what I had or its condition.

Yes, I thought of that after I posted...with the crimp closed on a 2&3/4" shell, that would not automatically mean there's still room in the chamber for the crimp to open. However, I specifically checked for a chamber step and there is none...just a continuous taper into the bore. But, for safety sake I figured its conceivable there could be a remote chance that the crimp might open into the beginning of the taper causing a pressure situation.

So what I did then was take a once fired Win AA hull, ensure the crimp was flared fully open and straight, packed the hull tight full of shot all the way to the top, and put tape across the open end...which by the way, also meant that excess tape came down all around the circumference of the hull's dimensions, making the end even a little larger in diameter.

But the fully extended and taped shell still slid right in and out of both bores normally, action still closed and opened normally, extractors lifted the shells out normally, etc. So it appears a 2&3/4" shell should be fine, but opinions to the contrary are welcome.

There will not be any definite step from chamber to bore. Don't forget the considerable leverage the gun has to push that shell into the chamber, you may not feel the resistance. The best way would be for a gunsmith with the proper tools to measure the chamber. Another practical option is to take a 6" machinists scale ruler and slide it into the chamber. Usually you can feel where the forcing cone starts. Mark with your thumbnail and read the depth.
I admit that the 2 3/4" plastic shell used in what is probably a 2 5/8" chamber is not going to be a big deal. The plastic is thinner and slicker than the paper hulls of the past. Especially if you are going to stick to black powder. One drawback of the plastic hull will be deposits of melted plastic which may accumulate at the chamber mouth due to black (or Goex's) higher burning temps.
Post some pictures if you can of the gun and it's proofmarks. I am sure someone will have more info on your gun than I do.

Some of the early breech-loaders were "switch hitters" in that they could be loaded from the muzzle and/or breech. They used a Maynard-type "pin hole" brass shell and were externally primed with a common musket cap on a nipple connected to a flash tube aligned with the pin hole in the center of the shell's base. Wm. Miller's Nov. 1866 T-Latch patent described Charles Parker's first shotgun as both a breech- and muzzle-loader.

Converting a breech-loading hammer gun to a cap-lock could (on the first level of analysis) simply involve removing the firing pins, fitting nipples and converting brass or steel central-fire shells by modifying the primer pockets. The only advantage of this, so far as I can see, would be to use an old double shotgun for the muzzle-loading deer season???

In reality, the conversion, to be craftsman-like, would involve some TIG welding to: (1) modify the hammers to have cups to shield the eyes from shattered cap fragments, (2) adding fences to the bolsters for the same purpose, (3) reconfiguring and taping the firing-pin tunnels to accept the screw-in nipples and, perhaps, (4) narrow the tunnels into more efficient flash tubes, all of which would involve some stress relief and re-case-hardening. None of this would be rocket science. The only-known Parker breech-/muzzle-loading T-Latch s/n 06 is pictured in both of my "Parker Guns" books. EDM

Kinda like teets on a boar hogg.

Thanks!

I have posted the use of a 6" machinist scale here several times. It is very unlikely you will be able to "Feel" the beginning of the cone. Instead with bbls removed point them toward a light source, as a window. You can get your eye behind the bbls & looking inside see the cone as a shadow. Slide the scale in so you can still see the cone & you can watch for the corner of scale to just touch the shadow line. Do this several times till you are sure you are getting consistent readings & you will quickly see you are well within ±1/32" which is all the accuracy you need for this job. A precision made chamber gauge which just happens to measure .001" larger than the chamber end (Not at all an unusual condition on old chambers) will show far more error than this.

Yes, I've noticed a dark ring when holding the muzzles towards a light and first thought it was a 'step' at the front of the chambers, but then when I felt no step with the rule, I assumed it was the beginning of the forcing cone...I'll get it ID'd better tonight...thanks

With a tiny high intensity white light about the size of a big wooden kitchen match stick, I could get right into the chambers and the "ring" I was seeing when I'd look through the barrels at a light, was the beginning of the forcing cone that had a different surface coloration than the chamber walls themselves. The skinny high intensity light also allowed me to get the 6" machinist's rule right in there with excellent visibility and the chambers measure 2&5/8" to the edge of the different colored area at the front edge of the chambers.

Taking another once fired Win-AA hull, I flattened the edges of the fold marks of the crimp with a pair of flat-billed pliers so the sides of the hull continued right on up straight to the top of the crimp section. I then fully packed the hull with #9 shot, wrapped a piece of heavy cellophane packing tape around the top half of the hull with an inch sticking up past the top, then folded that excess down / across the shot like you'd fold the end of a coin wrapper.

Holding the barrels in one hand with the extractors relaxed in and flush, the fully extended shell slid right in all the way each time, with light even pressure the whole way...I was looking to see if there would be a possible increase in pressure during that last quarter of an inch or so but could not detect any change...there was light, even drag the whole way in...and mind you with probably an additional .020" thickness to the hull dimension from the packing tape wrapped around it. So based on all the above, it appears that normal, plastic, .12ga star crimped 2&3/4" shells should be fine.

Ordered some barrel hones...hope to have this thing ready in a few weeks and I'll post some pics...thanks again for the advice & counsel.

You might be better off to weld her shut and drill some nipple holes.

I just randomly measured a few nominal 2 3/4" fired hulls, Win AA (old style) Rem RXP & all were a full 1/16" shy of the magic 2.75" or about 2 11/16". Thus with a 2 5/8" chamber you are looking at a hull only 1/16" longer than actual chamber. "IF" the load you put into that hull has presure compatable with the gun, it will never know the hull is "Too Long". Several American Companies purposly cut their chambers to only 2 5/8" for use with 2 3/4" shells.