Some time ago I bought a second drilling, because I liked my first one so much and I wanted one with external hammers. The "new" hammer gun was made in 1926 and chambered for 16 gauge/9.3x72R. Sellier & Bellot make this very old rifle caliber (the only company that does) so I ordered a couple of boxes (at a ruinous price, I might add) and took the gun out to shoot.
Fired rounds WOULD NOT extract. I actually needed a pair of pliers to get the fired case out after the initial extraction by the very powerfully leveraged primary extractor hook.
I began a hunt for the reason and a fix. Cleaning the chamber thoroughly, followed by a polishing with mild abrasive helped but not much. There was no visually evident roughness, but cases simply wouldn't come out without undue force.
The gun is actually marked "8.8mm/72" but this is more or less universally accepted among drilling shooters to mean the 9.3x72R, as German gun makers used bore diameter, not groove diameter, in their caliber designations.
Well, MOST of them did. Mine apparently did not: I slugged the bore and it came out as 0.358", not the 0.366"-0.367" that's used in factory- standardized 9.3x72R ammunition. The 9.3x72R came in several variations: it was in fact one of the first calibers "standardized" by the post-1891 German proof laws. I suspect my gun—which bears no maker's mark, something that's not unusual in drillings—was made by a moss-backed old-time gunsmith who simply continued to use the tooling and machinery he had in the shop. It's not unusual to find guns in this caliber with widely varying barrel diameters regardless of how it's marked.
The initial suggestion I received was that the large bullet of the S&B ammunition was causing an over-pressure condition. I tried mild reloads using a hollow-based bullet of 0.358" but still no joy: those cases stuck too. It clearly wasn't an over-pressure situation. I began to think about a deformed chamber: a bulge or non-concentricity would cause hard extraction. Accordingly I made a chamber cast with Cerro-Safe, a very low melting point bismuth alloy specifically designed to make chamber casts.
But the cast wouldn't come out, no matter what I did: I ended up having to melt it out with a heat gun. Obviously there was something wrong with the chamber even if I couldn't see it. My guess is that there is an invisible bulge somewhere, and the expanded case would come so far and no further because of it.
In my experience if a chamber has an issue it usually has it in the front: it may be due to throat erosion or perhaps an oversized round that generates enough pressure to deform the chamber a bit. The next step in the search for a solution was to cut the case back in hopes that the full length of it would be clear of the presumably damaged area. The damage wasn't visible but it must have been there.
I ended up cutting a couple of fired cases back to a total length of 54mm, and loading them with the 0.358" bullet and some Accurate Arms XMP5744. Today was range day to check. I was delighted to find that the short cases extracted without problems. A factory round I fired got stuck, as before.
So now I have what I guess is my first "wildcat" round, which I'll call the "9x54R." I'm slowly accumulating more cases and in time will have enough to be able to sight the gun in. In essence I have "re-invented" the .38-55 Winchester, with a slightly smaller-diameter bullet.
Doing this job required a couple of tricks. First, because the internal case diameter is too big to hold the 0.358" bullet (as of course it was intended to use a 0.366" bullet) I resized the necks in a sizer for...the .38 S&W! The same die set has a seater than puts the bullets in to exactly the right depth and crimps them in place. A Lee #3 shell holder works with the rim of the case, so I didn't need a special holder.
Then I ran into an oddity with the primer pockets. Oh, yes, the S&B cases use Boxer type primers, but the primer pockets are too small for a Large and too large for a Small American primer. They got reamed out with a special tool used to remove crimps from military case primer pockets. Once adjusted to the right size for an American Large primer, I had no more problems. Interstingly I didn't have this problem with S&B brass in the 8x57JR ammunition I use in my other drilling.
I want to use a heavier bullet. The .38-55 is listed with a 250-grain bullet, but the 9.3x72R comes with a 193-grain bullet. The lead RN bullets I'm using weigh 163 grains: respectable, but I like heavy bullets for additional momentum and penetration. I've ordered some 200-grainers from Midway and 250's are available, but then I get into questions about rifling twist rates.
Load data for the .38-55 will work with this wildcat which is in effect a .38-55 with a slightly smaller bullet but a very slightly longer case (the .38-55 has a 53mm case length). Other than the slightly smaller rim and the necessity to load a smaller bullet (the .38-55 uses a .377" bullet, much too large) the differences are minimal. In keeping with the European origins of the gun and the ammunition, "9x54R" seems right: but ".358-54 NRVO" would also be appropriate! SAAMI chamber pressure for the .38-55 is 30,000 CUP, well within my drilling's capability.
The .38-55 has a respectable reputation on deer, especially with heavy bullets. When I get this beast shooting what I like and where I want it to, I'll take it into the woods. Maybe not this season, though. Lots of development work to be done.
Update: August 27th, 2015
The 200-grain bullets have arrived. I now have 5 cases, and these have been loaded to match a .38-55 load listed in Cartridges of the World. The charge is 25.5 grains of XMP5744, which COTW rates at 1853 FPS. Assuming they shoot reasonably well, this will be entirely adequate for my purposes. The bullet is a cast flat-point with a gas check. It's 0.357" in diameter, and I would have preferred a 0.358-.359" diameter but this is what I could find. We'll see. Watch for further developments on the "9x54R" wildcat!