B.N.P.
 

Hello alls
I want to know what mean exactely those numbers in the british proof:
9 m/m "152" 13 tons........the "152"
7.65 m/m "350" 12 tons.....the "350"
45 "900" 7 tons...........the "900"
So in the 'Constanzo' I don't understand the explain about the cal
30 to 172.28
9m/m to 118.35
Thanks to all can help me like if I was a little kiddy

172.28 and 118.35 are the number of lead balls of the measured barrel diameter which would equal one pound. Though this system went out of use in 1910 (in Germany, I don't know about elsewhere), we still see it today in shotgun "gage" bore measurement.

No idea abut the othe part of your question, sorry.

--Dwight

The "13 tons" relates to the British method of proof. It is the pressure of either the proof load or the working load it was proved for. The British method of measuring pressure is to actually measure the back thrust and then calculate the pressure from the back thrust. This method usually results in numbers lower than those resulting from the SAAMI methods of measuring pressure.

As a practical matter, the SAAMI method correlates better to the pressure required to blow up the piece while the British method correlates better to the amount of wear and tear the action will be subjected to in extended use. Bottom line for either method is to use an over pressure load to prove the piece is safe at the standard working pressures.

The "13 tons" means an indicated pressure of 13 tons per square inch. Here in the US we are used to speaking in terms of pounds per square inch while in Europe they use bars. Neither the British method or the SAAMI cup method yields numbers as large as the true peak pressure.

Thanks "unspellable" I have understand for the tons :it's the same on french weapons with bar but the number 152 or 350: what doe's it means ??