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:?: British guns bearing Birmingham proofing have markings including, for example, 3 1/4T, 2 3/4" and 1 , 1 1/8 or even
1 1/4 oz. The English employ the long ton (about 2200 lbs, I believe) but I still cannot make that add up to, for example, 8000-10000 psi chamber pressures of some light game loads for a 12, 16 or 20 g shotgun. Can someone help with the conversion or translation?? Thanks
 

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Unfortunately can't help you directly, but this is the web address of the Birmingham Proof House here in England. You could try dropping them a mail.....

http://www.gunproof.com/

Good luck.

Ben
 

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For general pressure conversions try:
http://www.ex.ac.uk/cimt/dictunit/ccpress.htm

now to your question:
The British and the russians as well as the Irish mark their guns with their everyday service pressure, not the proof pressure.

So you do not need to fire them at only about 3/4 of the marked pressure, like you would do with guns of other countries.

The British give the information in three ways:
As the pressure you should use, as the maximum shot load you should use, eg 1 1/4 or 1 /1/8oz (ounces) (about 32 grams), or as the proof mark (symbol (crown) with eg NP underneath it).

If you are given the max. load then just use good quality shells of that load.

If you have the proof symbol post it

It is not possible to straightforwardly convert british proof marks since the way of proofing (the pressure measuring transducer is different from the ones used in other countries.)

I am sure I have seen conversion tables somewhere....
 
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