Mystery drilling rifle chamber - 8,8mm x 72?

[Rotaman]

I have been inspecting a drilling that the owner tells me is chambered in 9.3, but he is not familiar with firearms and has no other details to share. I asked to see the proof marks and the barrels are stamped with “8,8mm” (or maybe 8,6mm — the second digit is kind of mushed up at the top). Beneath that is stamped the number “72”. My thought is that the rifle is chambered in 9.3x72, but the 8.8mm designation makes me wonder if it’s actually the more rare 8x72R. Is anyone able to enlighten me on the rifle barrel’s actual chambering? Photo attached. Thanks

[algmule]

Hello

8,8 mm = bore diameter. Add groove. I say 9,3x72R. I am not familiar with any bore diameter 8,6 mm with brass length 72 mm. Others may be. 8,7 mm bore and 72 mm brass length I have seen but not 8,6 mm. Could be I am wrong. Slug the bore with a piece of lead if you are unsure.

I own two Drillings in 9,3x72R (one 12-12/9,3x72R and one 16-16/9,3x72R). Both wear the 8,8 mm marking for bore diameter.

Peter

[Rotaman]

Thanks Peter!

[mike ford]

Rotaman,
Your rifle's bore diameter is likely 8.8mm, but not necessarily. The dimensions of 9.3x72 barrels vary a great deal and groove diameters of from .352-.368" have been found. Peter's advice to slug the bore is good advice. Be aware, however, that many barrels (especially older ones) have an odd number of grooves, making measurement of the groove a little complicated, because they are not across from each other. The good news is that193 grain flat nose jacketed bullets loaded in current 9.3x72R ammo are especially designed to be useable in barrels of differing diameters, without unduly raising chamber pressures. For handloaders, appropriate jacketed bullets can be found in several diameters, just don't use .365-.366" jacketed bullets intended for more powerful cartridges, such as 9.3x 62 or 74R. Cast bullets can be made in any required diameter and are perfectly acceptable for barrels in good shape.
Mike

[algmule]

Hello

The bore was any of the possible measurements in red when the rifle barrel left the Beschussanstalt circa 1911-1912. i.e. a plug gauge of 8,8 mm got through the bore but not one of 8,9 mm.

8,80 mm
8,81 mm
8,82 mm
8,83 mm
8,84 mm
8,85 mm
8,86 mm
8,87 mm
8,88 mm
8,89 mm
8,90 mm

The old "gauge measuring system" had the following: i.e. more possible bore diameters with the old gauge measuring system between the plug gauges. Or fewer plug gauges if you want it that way, that is. Some say 108,49 was the more frequent on 9,3x72R:s but almost all rifle barrels for 9,3x72R marked after the the old gauge measuring system I have seen have had the 118,35 marking.

118/35 = 8,64 mm
108/49 = 8,89 mm
99/70 = 9,14 mm

555.jpg

As Rotaman’s Drilling is post circa 1911-1912 (mm marking/measurement) the options in red in above “chart” were the ones possible for bore diameter when it left the Beschussanstalt. Had the bore been tighter than 8,8 mm the marking would have been 8,7 mm. Larger than 8,89 it would have been 8,9 mm.

Mike,
Glad your back and "up and running". You have an e-mail from me which is a few weeks old. Nothing important, though.

Peter

[mike ford]

Rotaman,
Peter's experience with pre-1911-12 9.3x72R barrels is the same as my personal experience, but others of my knowledge offer that 108,49 is more common to them. I can only recall seeing one marked 99,70. In my experience, most rifles marked 118,35 have .358-359" groove diameter and those marked 108,49 have around .362" groove diameter, so yours should be between these diameters, closer to .362".
Peter,
Thanks for the good thoughts, I will look for the email.
Mike