doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Drilling caliber marking

I also have a C. Srba of Heidelberg system Buchel target arm in a tight 8.15X46R with a "181" stamp just below the "Crown" over "U" and above the December 1903(12.03) stamp. There were other target arms in 0.22"(5,6X15R) and other small bore calibres. Does anyone have one with pre-1910 odd stamps?

Kind Regards,

Raimey
rse

I'm delighted that my "innocent" original question triggered such a profound and meaningful debate. I suspected that the 248 on my early drilling could be a gauge expression of 7mm caliber, but not being a mathematic type I hoped others will help. Thank you very much so far. - Jani

.284 inch equals 7 mm in the United States in a Winchester rifle.

NOT .248 ---- BUT .284

http://www.gunbroker.com/Auction/ViewItem.asp?Item=118472625

Check out the pictures here of a .284 Winchester Model 88

In my very limited experience it is very rare to find the actual rifle caliber marked on a Hammer Drilling. I own 2 of them, neither of them are marked with what they shoot. I own a cape gun, it is not marked with what it shoots. I have learned how to cast chambers and throats to determine the correct cartridge to use. Jent

Jent, we are aware of the meaning of .284 in inch system but we are talking about 248 (not .248) in gauge system. - Jani

Steve, The side by side barrel vice that you got for me is great !! I have been using it regularly. I love it. It was the best thing at The Vintage Cup 2008 that I saw. I am very glad that I bought one. Jent

montenegrin, I can send you some CEROSAFE, maybe, and you can make a perfect casting of the chamber and throat of your drilling rifle barrel and you will then KNOW exactly what your drilling is chambered for and rifled for. Jent

There is no telling what it would take to ship a little CEROSAFE to Slovenia from Virginia.

Do you ever see any ammo for a 6.5 mm X 72R cape gun in Slovenia ??? If you do is it BOXER primed or BERDAN primed ??

Jent, thank you sincerely for your kind offer but I realy don't need Cerosafe as I do my chamber/throat casting using just candle wax - with perfectly useful results for the purpose. The reason I haven't yet do it for this drilling is lack of time (I just received it from Germany and had to register it right away, and needed caliber info for the registration).
I'm not familiar with 6.5x72R but somewhere I have a round or two of 6.5x70R - the "pencil cartridge". These are old berdan type and are considered collectors items.
-Jani

As always Steven is correct: "The loads for caliber .454-.299 inches(7.62mm), however, are not designated in the usual millimeter system used for rifled bores, but with the designation customarily employed for marking smoothbored barrels, that is caliber 51.05 - 172.28. The designation here is borrowed from the old British method of indicating the number of lead balls fitting the bore which can be cast from one pound of lead." - Gerhard Wirnsberger

And also from the same: "For calibers not listed in the proof table, the person submitting a gun for proof must furnish load data in writing, as well as suitable cartridges, free of charge, to the proof master."

In 1676 Essen was using the gauge mark for plug gauge diameter, so I would think the trade had plug gauges below 172,28 but wouldn't think the trade to stamp the gauge on the tube for the proofhouse in the preliminary stage but rather the proofhouse to have plug gauges smaller than 172,28 but not load data, which would determine the threefold powder charge and double shot charge weight for the 1st proof, or cartridges.

Kind Regards,

Raimey
rse

A 7m/m bore dia would be a 222 gauge based on two methods of calculation both of which give same result:
UK Proof Formulae with lead having an s.g of 11,352 (gms/cm3)
and 1m/m= .03937"
Dia in Inches = 4.6578 divided by N ( Number of gauge)
Result 222
or long hand volume of sphere = 4/3 pi r3. r=3,5mm , r3= 179.573mm3, 11,532gms x .1796 = 2.039 gms, 1lb lead = 453.515gms. 453.5 divided by 2.039 = 222.

248 is not gauge number.
Good luck with your new gun, if it is 7X57R then it should be a nice, useable gun. Post back with photos of a hunt.
Regards Hugh Lomas

Hugh;
No problem with your math, but I would point out, the 3√ of 4.6578 is 1.670". All the British proof charts I have ever seen give a 1 gauge as 1.669". True only one little ol thousandths of an inch, "But", it don't fit the charts perfect, 4.65148337 does. This does not exactly fit however any listing I have ever seen for the density of lead, but the math is otherwise perfect. My Machinery's handbook incidently give the SG of lead @ 11.342 rather than 11.352. For the formula to perfectly fit the charts requires lead to weigh in @ .41059 lbs per CuIn or 11.365 gms/cm3. The 11.352 wt is closer than 11.342, but neither is quite heavy enough to fit perfect.
.276" (222) is nominal bore dia for most bolt action military 7mmm Mauser rifles or .008" under groove dia of .284". This of course does not guarantee that some German maker of a Drilling did not make a 7mm with a tighter bore than this. Undersize bores with deep grooves seem to me to be rather common on German rifles.