doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Proofmark puzzle

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Seems the Brits are pulling & driving the Proof Ox-Cart & all others are basing their Proof Rules on the British Scales. The Brit's March 10th, 1896 Rules Update directed that Choke Bores tubes to be proved w/ Nitro Powder to be acknowledged to the Proof Compagnies in writing by the sender and that the tubes would also be subjected to a Proof w Curtis & Harvey's No. TS2, or a powder that was equal in all respects. Curtis & Harvey's No. TS2 was a fine grained black powder. The Proof Compagnies decided that with the every changing variety of new fangled powders in addition to the primary Schultze or E.C.(Explosive Company) that the sender could very well choose another powder but the powder must achieve a stress of 80% over the Service Charge and under 100% of the Service Charge. Scale No. 6 was the gospel and everything else based on it. Then the Service Charge Powder & associated Shot weight were to be marked on the Barrels:

MaXm - SCH. ?? Grains & Shot ?? OZ.

Then one finds the Germans draggin' their feet behind the rest.



Hochachtungsvoll,

Raimey
rse

And these are the earliest actual pressures I've found - don't forget + 10 - 14% for transducer numbers
Black and Nitro powder Service and Proof Charge Pressures - note the C&H TS (treble strong) black powder pressures are similar to the new fangled bulk smokeless
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA296&dq
Experiments to ascertain the pressures given by service charge and proof charges used in England have been carried out by The Field. Under the existing Regulations of Proof in England, a “service charge” is specified for every bore, and the compulsory definitive proof is made with double the service charge of proof-house powder and 1 1/3 (times) the service charge of No. 6 shot. Besides the compulsory proof, a supplementary proof with other kinds of powder is permitted, if applied for. Many other charges, both larger and smaller than the officially stated “service charge”, are in constant use.

Powders used for proof are given as T.P. (Tower Proof) “which shall be of strength equal to Waltham Abbey “R.F.G. 2” and of grain varying between Nos. 4 and 5, that known as Curtis and Harvey's “T.S.” (Treble Strong) No.2 [for Supplementary Nitro Proof with 4 1/2 Drams and 1 2/3 oz. “soft” No. 6 shot] and, that known as “Col. Hawkers Duck Gun Powder”, and the nitro-powder known as Cordite, or any other description of nitro-powder which may hereafter, from time to time, be adopted by His Majesty's War Dept.”



Modern piezoelectric transducer pressures would be 10 - 14% higher.
12 bore
Nitro 1 1/8 oz. with 42 grain Bulk Smokeless = 3 Dr. Eq. (1200 fps):
5330 - 6110 psi
Nitro 1 1/4 oz. with 45 grain = 3 1/4 Dr. Eq. (1220 fps): 6360 - 8620 psi
16 bore
Service charge 1 oz. 2 3/4 Dram Eq. (1220 fps) = 38 gr. Bulk Nitro powder.
C&H “T.S.” No. 4 BP - 7,480; “Schultze” - 8,250 psi; “E.C.” - 8,960 psi
20 bore
Service charge 7/8 oz. 2 1/2 Dr. Eq. (1210 fps) = 34 gr. Bulk Nitro powder
C&H “T.S.” No. 4 BP - 8,240; “Schultze” - 8,220 psi; “E.C.” - 9,100 psi

Great info and it would seem that all are trying to establish a Baseline Pressure of 8.8k PSI.

I guess posting a foto of the British Scale No. 6 might be interesting but there aren't associated pressures.

Hochachtungsvoll,

Raimey
rse

British Proof Scale No. 6-1896


French Proof Table.


Hochachtungsvoll,

Raimey
rse