doublegunshop.com - home Forums Thread Like Summary - 9mm Question

I hate to keep asking questions, but I bought this Drilling on Gubroker a couple of weeks ago: https://www.gunbroker.com/item/937002974

It turned out to be really nice and marked "Deutsche Waffenfabrik Georg Knaak, Berlin S.W. 48 Germany" on the rib.I don't have a clue as to the maker. Made in 1929. Extremely nice condition and finish with essentially perfect bores. It turned out to be a lot nicer in person than in the ads.
I told the seller when I purchased it that it was almost certainly a 9.3 x 72. The ad was wrong on both guesses. When I recieved it, I could examine the proofs closely and it was marked 8.8 72. I put a new case in the chamber and it
seemed to fit perfectly. I then slugged the bore with a sized and lubed .365 bullet ( 9 BNH). Almost never got it started but got perfect land and groove (6 groove) impressions. When I measured both with good calipers, It turned out to be a perfectly spec'd 9mm barrel. No doubt about this; no between size maybes. I had heard about this, but in the several vintage 9.3's I have owned I have never run into it. I fireformed a case to the chamber with a good charge, on the off chance it was a 9x70 R Mauser, but the formed case measured exactly to the chamber specs.

My question is, what is the normal practice in this situation? I plan on taking sized cases, neck sizing only in a 9 x ?? die and loading some gas check 9mm bullets to start.The neck will need to be annealed every few shots to keep down splits, but shooting the 9.3's will really raise pressure and there was so much lead squeezed off while slugging that it has to hurt performance. Does this approach sound reasonable?

As an aside, I purchased a Scherping O/U Combination gun from 1920 ( https://www.gunbroker.com/item/937298063 ) this evening. It was advertised as a Drilling but was a 12 over 8x57. It looks to be a gun that will clean up well, and the company selling it is only 6o miles from my home. I think it will be an interesting piece.

AGS,
Your drilling Is very nice and is not very unusual for a 9.3x72R. Most seem to have groove diameters of around .362", but a significant number of them have groove diameters of around .358". Some others are larger, up to .368" and some are smaller, down to .352". This is complicated by some barrels being hard to measure because of having an odd number of grooves. This cartridge was popular for a very long time, beginning before hardly any of the dimensions were standardized. This includes the "shape" of the case by the way. To bring some order to this, and effort was made "normalize" the dimensions of this and a couple other cartridges, such as the 8.15x46R. As part of the effort, a special bullet was adopted that is safe in the varying diameter barrels. For lack of a better description, the bullet depends on a "driving band" to take up the space from the smallest to the largest diameter barrel without increasing the pressures to a dangerous level. If you only intend to use factory ammo, all of it, that I know of uses this type of bullet. If you intend to handload, .357-.359" bullet molds and jacketed bullets are easier to find than appropriate 9.3mm bullets are, and cheaper too. You should use bullets appropriate for 35 Remington, the new "Flex-Tip" bullets seen to be receiving good "press" now. You should avoid 9.3mm bullets that are intended for more modern cartridges such as 9.3x57/62/64/ or 74R. Raimey mentioned that your rifle is "express proofed" ( crown E proof mark). This proof is a little "stronger" than the normal 18,000 CUP pressure but does not represent a "magnum" proof and should not exceed 20,000 CUP. I hope this helps.
Mike
To expand on Raimey's comments, above, I load for a 9.3x72R which is also "Express Proofed". I do not use black powder and do use a filler (a tuft of kapok, tamped onto the powder), but fillers are very controversial and you have to decide for yourself whether or how to use them. I use a 208 grain cast bullet (old H&G mold #512c) with Red Dot or Unique and the kapok. For jacketed bullets I use the 193 grain RWS bullet, from a "stash" I brought back from Germany, or from another "stash" of S&B 193 gr bullets. I have tried 200 grain RN .358" bullets and find them satisfactory. With jacketed bullets, I use medium burning powders such as H/IMR 4895 or 3031. If you decide to use fillers, you must work the load up with the filler. Never add a filler to a load that was worked up to full velocity without the filler. Otherwise, loading is pretty straight forward, if you use a 3 die set. The die set I use was bought as a 2 die set and I made the third die from an "M" die by adding a self-made expander. The third die is necessary because of the straight case. Also using the sizing die w/o the regular expander sizes the case down enough to hold the .358" bullet. If you have 9.3x74R dies, you can neck size the 9.3x72R cases with the FL sizing die and seat the bullets with the seater. I loaded 9.3x72R this way by expanding/belling with a self-made punch type expander, until I found 9.3x72R dies.
Mike

oskar,
Good show. If you run out of coyotes, you are welcome to as many of ours as you want. A 1907 drilling is a little but late for lead bullets but if it is intended for them the barrel might be marked for Blei (Bl.), If for jacketed bullets, KmG or StmG.
Mike