Copper Crusher Cylinders Tony Edwards Collection

The attached picture shows a wooden box containing copper crushers from Tony Edwards collection. It has a Royal Laboratories painted stamp at the bottom. Can anyone tell me what they were used for please and how rare they are? It is for sale if anyone is interested, money to Viv.



Involved in measuring chamber pressure?

The British method was - as might be expected - very different from the radial pressure measurement used on the continent.
I do not have detailed knowledge of it, but basically it measures the base force acting on the bolt face, using a well oiled case.
The original bolt is replaced with a pressure bolt so that the base force deforms a copper crusher within this device. It could be, the photo shows this UK crusher type. I have never seen one.

The advantage of this method is that you need no special pressure gun, and no drilled case. The disadvantage is that pressure figures obtained this way are very different from the CIP/SAAMI figures. British 9 mm is a case in point.

CIP/SAAMI copper crushers are little cylinders, diameter something like .28 in (several sizes exist), and have no central hole.

An example of a pressure gun using copper cylinders but not necessarily the same as for what Buster shows ?


I believe JPeelen’s description of these cylinders being part of the British, or Whitworth oiled-case system of measuring pressures is correct. The hole in the cylinders is for the passage of the firing pin. The end result is the same, the cylinder being crushed or compressed and the amount of shortening compared with known tarage tables. It was never very successful especially as more modern powders were developed.

A very nice collectable for anyone who would collect such things.


Gents thanks for all your helpful replies.



Just a question - is any ammunition manufacturer anywhere still using lead or copper crushers for pressure measurement? I’d think that piezo gauge measurement would by now be universal, even in third world countries…