Lagopus;

Thank you very much for your informative information of the concerns of the Proof Master about sleeving of shotgun barrels in the mid 1950's.

Would you be so kind as to elaborate on the following sentence of your above writing: "The Guardians initial reaction was to tell the Proof Master to refuse to prove them and in the interim they decided to get a specimen and subject it to a 20,000 standard service cartridge test. in March the London Proof House agreed with their actions." What is a "20,000 standard service cartridge test"? Is this 20,000 pounds per square inch (psi)?

Kindest Regards;
Stephen Howell