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gitano 10-20-2010 12:51 PM

Drilling: G.F. Stormer: Initial Workup
Go here: for the story on how I came to own this piece.

As I said in the above thread, I thought the chambering was 10.75 x 58 Krag Petersen. It isn't. I cast the chamber and slugged the bore, and it's longer and 'wider'. Now, I think it is one of the following.

In order of likelihood of being correct:

1) 11x60 Gras

2) 11.5x57 Spanish Reformado

3) 45-90 Winchester Center Fire

There are "problems" with each of the above. I think a table containing the dimensions of each of the above cartridges and the chamber casting will facilitate the comparisons best.

As you can see, there's something "wrong" with each of the 'candidates'. For example, the 11x60 Gras is close in head diameter, neck (mouth) diameter, and case length, but the caliber is larger than the 0.445" of the Gras and most importantly, the chamber does NOT have a shoulder AT ALL. And so on.

I measured the chamber casting every 0.125" from head to mouth, and graphed the results which yields a profile of the chamber. I don't find any cartridges in Donnely's book that match the dimensions and the shape of the chamber. Here's what the graph looks like. (I "squashed" the top image to exaggerate the taper just ahead of the head so it's easier to see.)
Basically, the taper is 0.010" per 0.125" of case length for the first ~0.625", then it's ~0.003" per 0.125" of case length to the mouth.

A .348 Win still "works" as a starting point. I 'beat' on on 'til I could get it to chamber, and then loaded it for fire-forming and formed a case. That was actually what got me off the 10.75x58 Krag Petersen immediately.

Here is a picture showing from left to right a fired .45-70 Gov't case, the abused .348 Win case after fire-forming, an 'unabused' .348 Win case, and the chamber casting.

The fire-formed case looks so bad because of the shape of the chamber with that sharper taper near the head and more gradual taper to the mouth. Looking at the chamber cast it's difficult to see those two different slopes. Since the rim and head of the .348 fit the chamber so well, and the .348 is a sharply tapered cartridge, I thought it might just 'drop in'. Au contrare. The width of the .348 Win about half way up the case is larger than the chamber. As I 'squoze' the upper body of the .348 to fit the chamber, the lower body expanded. There was a lot of grunting and groaning and the result was 'ugly', but in the end it fit the chamber and after fire-forming provided useful information.

The rifling of these old Central European combination guns are complex. (It's often similar to "Whitworth" rifling.) There are at least three and sometimes four separate diameters. This piece was advertised as a "10 mm caliber". It isn't. It is at least an 11 mm caliber, and probably an 11.15. However, how do you decide which it is when there are four diameters to choose from?

I measured the bore (in all it's various dimensions) from the chamber cast. The result suggested that it might be some sort of .45 caliber, maybe even a .458" (11.5mm-ish). I dropped a .45-70 bullet into the mouth of the fire-formed case, and it fit just as expected for a fired case - nice slip fit.

I was beginning to believe that it might be a .458" (11.5mm-ish) of some sort. Not assuming that the muzzle end of the bore had to be the same as the breech end, I took a lead bullet that was nominally .458" (.459" actually), and pressed it into the muzzle. It didn't get far. However, the measurements from that bullet engraved at the muzzle, were identical to the measurements just ahead of the throat from the chamber cast. Quality gunsmithing. :D

Clearly a .458"-ish bullet was not going to work. I knew this bore was larger than the Collath's, but just to make sure, I pushed one of my bullets cast for the Collath - 0.423" (10.75mm) - into the muzzle. Only the highest lands engraved the bullet. So, the 'caliber' is somewhere between .423"-ish (10.75mm) and .458"-ish (11.5mm). I'm thinking it's 11.15mm or something near .452"-ish. I have a mold for casting .45 caliber bullets (nominally .452" bult probably .453" or .454"), for my .45 Colt, but I haven't used it yet. I will get it out today and make a couple to use see how they fit.


I am going to send Hornady some drawings and a chamber cast and have them make some dies for me. Might as well get the pieces that make cases to fit the actual chamber dimensions. I don't really care if it is some "known" cartridge.

I intend to use .348 Win brass. If necessary, I will get a reamer from Dave Kiff at Pacific Tool and Die and make a "forming" die.

I will see how the bullets that the Lee .452" bullet mould throws, fit the bore. Since this is most likely a black-powder-only situation, I'll be using lead bullets anyway.

This cartridge is very similar to the .45-90 Straight. I expect the charges and ballistics to be similar as well. Of course it's also very similar to the .45 Alaskan (a .348 Win blown out to .458), but the "Alaskan" is straighter and a .458" not a .452", so I'll start with loads from the .45-90. My .452" bullet mould (452-255-RF) throws bullets that are supposed to be .452" and 210 grains. I'm going to "make" a cartridge up in QuickLoad and see what external ballistics are like.

More when there's more to report.


branxhunter 10-20-2010 03:57 PM

Re: Drilling: G.F. Stormer: Initial Workup
Better than a Sherlock Holmes novel. Looking forward to the next instalment.....


gitano 10-20-2010 05:44 PM

Re: Drilling: G.F. Stormer: Initial Workup
So here's the next chapter in the mystery...

I started "making" cartridges and bullets in QuickLoad, and after a while of fiddling around, I had an "electronic" cartridge that I thought was going to be close to real, and some ideas about bullets. The cartridge will have to wait for some dies I think, but I got started on making lead, as opposed to 'electronic', bullets.

I decided to limit the pressure for the cartridge to 25,000 PSI. Quite modest actually, but with the right bullet, that 25kPSI was 'producing' pleasing ballistic results. For those that might be 'lurking', and to remind the 'regulars', my personal 'standards' for external ballistic performance are:

1) Deliver about 2000 ft-lbs of energy to max useful range, (for modern CF rifles, that's about 300 yds),
2) Keep muzzle energy to around 3300 ft-lbs, (this keeps recoil to my personal 'comfort zone'),
3) Keep total vertical deflection from muzzle to max range to 12" or less, (bullet flight plus and minus line-of-sight (LOS)),
4) Have an impact velocity sufficient to cause the bullet to perform terminally as designed.

There are only a couple of .454"-ish caliber bullets available to me that have ballistic coefficients above .15, and the best of those is .250 if I remember correctly. However, there are a couple of .458 bullets that have better BCs, one of which I already use - Lee's .459-500-3R. I have been using that in my .45-70 and as the core for my hand-made jacketed .50 Alaskan bullets. The BC for that bullet is .433 according to Lee, and .429 according to my BC calculator. It is not difficult to squeeze the .459" bullet down to .441" using Lee's bullet sizers.

I decided to use that bullet as a starting point, and simply shorten it to get lighter weights as I wanted them. I made three of them: The original-weight 500-grainer, a 404-grainer, and a 357-grainer. Here's what they look like flanked on the left by a 130-grain .308" HP and on the right by Barnse's 85-grain "X" bullet in .257:

Recalculating the BC for the otherwise unaltered bullet (500 grainer) I get .460. that looks reasonable. Here is QL's output with that bullet:

Muzzle energy is good at "only" 2943 ft-lbs, but this firearm weighs only 6.5 lbs so 2900 ft-lbs will be right 'up there'.

The bullet carries 2000 ft-lbs out to about 220 yds but has dropped about 14" below the LOS for a total vertical deflection of about 17". Impact velocity is only about 1340 f/s, but with this solid lead bullet, and based on my experiences with the .45-70, that's plenty for North American game out to 220 yds. I seriously doubt I would use this firearm with it's open sights at ranges greater than about 200 yds unless it was on a bison standing broadside.

So I made a 400-grainer. The BC drops to .370, but of course the MV goes up when the max chamber pressure is maintained at 24,500kPSI. Here's what QL predicts for that bullet:

ME is up to 3170 ft-lbs. It carries 2000 ft-lbs out to about 212 yds, some 8 yards short of the 500-grainer. However, at that 212 yds, it has only dropped ~7" below the LOS (half the 500-grainer's drop) making the total vertical deflection about 10", and impact velocity is up to almost 1500 f/s. More is better. Again, fine out to 200 yds for sure.

Most of the "big calibered" European cartirdges of the late 19th Century seem to use bullets in the 300-grain weight class, so I decided to shorten the 3R a bit more. It can't be shortened too much more because there would be too little bearing surface left. With the long nose that generates the higher BC there's just not much room left in a sub-400-grain bullet, but this 357-grain one has a bearing surface of almost 1 caliber. The BC drops to .325. Here's what QL says about that bullet:

Once again ME goes up. This time to 3250 ft-lbs. This bullet carries 2000 ft-lbs out to only about 200 yds. And again, the drop compensates for the shortened range. Total vertical deflection is about 7" and only 4" below LOS. Impact velocity is almost 1600 f/s. If I restrict my hunting ranges to 200 yds, this bullet still 'work's.

So, as is so often the case, since none of them "jump off the page", the 'telling tale' will be which bullet shoots the straightest. Only time will tell.


gitano 10-20-2010 07:31 PM

Re: Drilling: G.F. Stormer: Initial Workup
1 Attachment(s)
Here's a cartridge a fellow on a British forum suggested. I think this is it. It is called the 11.15 x 60R LK Express. The dimensions are right on, and a descriptions says:


popular calibre offered until the 1930's. Used in Drillings as well as other rifles. Semi-jacketed flat nosed bullet.
Maybe Hornady, Pacific Tool & Gauge, or Manson will have drawings and can make dies for me.

There's a picture of the 11.15mm x 60R LK Express below. Note the similarity to the .45-90 WCF.


branxhunter 10-20-2010 08:52 PM

Re: Drilling: G.F. Stormer: Initial Workup
Aha my dear Dr Watson, we have a result!

Now where is my pipe?

kombi1976 10-21-2010 08:28 AM

Re: Drilling: G.F. Stormer: Initial Workup
Fascinating stuff, Paul, as usual.
Wish you could bring that Down Under with you.
The goats would go down a treat!

gitano 10-21-2010 12:31 PM

Re: Drilling: G.F. Stormer: Initial Workup
1 Attachment(s)
Here's a better drawing of the chamber dimensions. I modified the dimensions of a case drawing found in Ken Howell's book Designing and Forming Custom Cartridges for Rifles and Handguns (page 561).

Dave Kiff at Pacific Tool and Gauge (PTG) knows the cartridge, but doesn't have a drawing. I'm trying to reach Lonnie Hummel at Hornady to see if they have drawings. If not, I'll send them the one below, and a chamber cast. I don't expect to hear from Hornady until next week, and if I place the order then, it will be 6 weeks before I get the dies.


sakorick 10-21-2010 03:41 PM

Re: Drilling: G.F. Stormer: Initial Workup
Excellent work as usual, Paul. Don't forget CH4D......they may be cheaper than Hornady and faster! Regards, Rick.

Jorge in Oz 10-21-2010 08:17 PM

Re: Drilling: G.F. Stormer: Initial Workup
I love your work Paul.

Check this cape gun/double its 12 gauge/32 Win.



kombi1976 10-22-2010 12:39 AM

Re: Drilling: G.F. Stormer: Initial Workup
That's a really nice Cape Gun.
I'm guessing 32 Win. means 32 Winchester Special (aka 32 cal in a 30-30 case) not 32 WCF which is 32-20.

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