doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 10 Gauge Manufrance Ideal with Lunette triggers

Ted, what am I suggesting? I simply quoted the proof book I have. I too have a French 12 gauge with double proofs, I certainly won't be shooting any hot loads through it nor would I suggest that anyone else shoot such loads through their century old gun. It's just nice to know (sweet!) that it has the extra stout proofs, don'tcha think so too!
Steve

Steve,
Double proof would have had three crossed wheat with crown marks, and would have been 20,500psi. Triple proof would have had four marks, and would have been 27,000psi, proofed with black powder. There exist Ideals proofed at the higher level. I'd still run low pressure ammunition in one proofed like that.
All I'm saying is it is an old gun, and what level it was proofed to 109 years ago might be a secondary consideration to using ammunition that would help keep it around for 100 more.

Best,
Ted

Ted,
Here's a scan of page 137 where I got my information from. Yes it refers to black powder, but peak pressure is peak pressure no matter whether black or smokeless powder was used.



FWIW this same document on page 136 also gave the information you quoted as well.

Steve

Also on my 12 gauge I like the heavier proofs because I feel they allow me to safely shoot heavier loads occasionally, if that's all that is available (such as when I was hunting ruffed grouse in the Alaskan boonies and ran out of my light loads).

Black powder was often used by the proof houses of various countries in the early years for proofing barrels which would be stamped with Smokeless Proof marks. As mentiones a fine grained black could be used to give the desired maximum proof pressure for the chamber. Thus for that purpose it mattered not which powder was used. The black however maintained a higher pressure for the rest of the barrel so was actually a more severe test than a smokeless charge giving the same maximum pressure. Later on special smokeless proof powders were developed which did away with the need for using black. As I recall the French marks for double, triple etc proof varied over over time. One has to correlate them with the point in time the gun in question was proofed.

All,
The book is not accurate.
The double palm is not double proof, but "epreuve superieure".
The triple palm is indeed the double proof which was actually twice the load vs the single proof.
These proofs were for the finished barrels only and used #2 black powder.
The following proof loads are in 12 Ga:
Single palm (standard proof for finished barrels): 10grams of powder and 60 grams of #8 shot for a 1170 kg/cm^2 pressure (16640PSI)
Double palm (superior proof): 14.5 grams of powder and 75 grams of shot with a pressure of 1630 kg (23184PSI)
Triple palm (double proof): 20 grams of powder and 120 grams of shot with a 2150 kg pressure (30580PSI)
Quadruple palm (triple proof): 30 grams of powder and 180 grams of shot for a 3050kg of pressure (43381PSI).

This was quite confusing and many people to this day have been incorrectly calling the double palm proof "double proof".

This gun was proved in the finished state with the load described on the flat. God knows what that pressure was, but for sure much smaller than the barrel proof.
That is the only one that the gun, rather than the barrels, is known to have survived once.

BTW, the pressures described in the book don't match the official numbers.

Best regards,
WC-

By way of illustration:



WC beat me to it, but, this gives you an idea. Further, very few guns ever received triple proof, denoted by the 4 crossed palms stamp, number 26 in the scan.

Best,
Ted

What would the marking "pression 850 kilos" equate to ? 5/8ths Proof ?

Nice find. You won't see many of those in your neighborhood duck blind. Gil

850 kilos stands for 850kg/cm^2, and was the pressure for the standard proof of finished guns for a very long time. In later days, it was changed to 900 Bars (almost the same) and then 1200 Bars IIRC.
WC-

Thanks Wildcattle, I picked up a Manufrance Simplex last weekend with those markings.