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What, exactly, is the CIP nomenclature on this box of ammunition telling us?




It occurs to me that in the era these shells were produced, I would have expected 2 3/4” CIP proof would be 1 1/4 ounce.

This is not recently procured ammunition, a friend bought them years ago and gave them to me. I should be more concerned that another hunting buddy has aged out, I know….

Best,
Ted

That the Sky is Falling.

Great Britain joined the Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives and adopted the CIP standards in 1980 but the new Rules of Proof were not introduced until 1984. Lead Crushers were used until 1989 when BAR was introduced, and the imperial proof marks could be requested from 1984 to 1989 using the Tons SERVICE pressure while the metric version used the Kg PROOF pressure.

The CIP transducer “Maximal Statistical Individual Pressure” for 50mm, 60mm, 65mm and 70mm 12g is 850 BAR = 12,328 PSI for a “Maximal Average (Service) Pressure” of 740 BAR = 10,733 PSI, and “Mean Proof Pressure” of 960 BAR = 13,924 PSI. Max. fps is 1,300 fps.
High Performance (Magnum) MSIP is 1200 BAR = 17,405 PSI for a Max. Service Pressure of 1050 BAR = 15,229 PSI, and Mean Proof Pressure of 1320 BAR = 19,145 PSI.

Both 65 and 70 mm 16g standard is SERVICE 780 BAR or 11,313 psi; MSIP 900 BAR or 13,053 psi; PROOF 980 BAR or 14,214 psi.
(The original 1984 chart indicates 16g PROOF 1020 BAR = 14,794 psi. The number was revised to 980 BAR in 2006.)

Both 65 and 70 mm 20g standard is SERVICE 830 BAR or 12,038 psi; MSIP 950 BAR or 13,779 psi; PROOF 1040 BAR or 15,084 psi.
(The original 1984 chart indicates 20g PROOF 1080 BAR = 15,664 psi. The number was revised to 1040 BAR 11-2021.)

Shot weight is not considered in the CIP standards

I don't know if British shell boxes are still labeled:
These cartridges are suitable for use in:
70mm case length: Guns with a chamber length of 2 3/4” or longer, nitro proofed to a service pressure of 3 1/4 tons per square inch (900 kg per square cm)
67 mm case length: Guns with a chamber length of 2 1/2” or longer, nitro proofed to a service pressure of 3 tons per square inch (850 kg per square cm)

A recent box of Lyalvale 2 3/4" says`..only be used in nitro proofed guns marked with a European Proof Pressure of 850 Bars or more`......

The newer laws don’t consider weight on shot charge. Hmm. Seems odd from here as the load was usually stamped into the barrels on the English guns I used to own.

Thanks for the info.

Best,
Ted

The British stamped the oz. 1896 until the revisions of 1954. At that time the pressure (Tons per sq. inch) was marked without the shot charge. 1989 it became BAR.

From an article in "American Rifleman" regarding the 1954 Rules

I can shoot ‘em in a French gun, I suppose…

Best,
Ted

Or a Stevens.

Vic Venters book "Gun Craft" contains interesting information on the rules of proof. When the Brits went from the 1925 rules (the first time that chamber length became a required proofmark), there was some confusion. Venters, in an interview with former Birmingham Proofmaster Roger Lees clarified it in a couple of sentences: "The proof loads now set down in writing (in the 1954 Rules) are almost in every instance the proof loading in use under the1925 rules. In general it may be said that under the new Rules of Proof, no arm will receive a more severe proof than hitherto."

Venters goes on to explain that the major changes which took place when Britain joined the CIP were that the new marks use the metric system and are now proof pressures as measured by transducers, not service load pressures. (Gun Craft, p.206._)

Probably the best data as to loads and pressures of British shells under the 1925 and 1954 Rules comes from Major Sir Gerald Burrard, The Modern Shotgun, 1955, 3rd Revised Edition Pressures converted to transducer psi from Long Tons/ Sq. Inch at 1”
12g 2 1/2” 33 gr. Nobel Smokeless (3 Dr. Eq.) with 1 1/16 oz. - 7,885 psi
12g 2 1/2” 33 gr. C&H Smokeless Diamond (3 Dr. Eq.) with 1 1/16 oz. - 8,288 psi
12g 2 1/2” 31 gr. Smokeless Diamond (2.8 Dr. Eq.) with 1 1/16 oz. - 7,179 psi