Parker Brothers 1893 Catalogue
“Our guns are bored on the latest improved system for shooting Nitros, or Smokeless Powder, and all our guns are tested with some one of the most approved makes, and a tag accompanies each gun, giving the results of such a (pattern) test.”
The Parker listing in the 1902 Sears catalog said "ALL ARE BORED FOR NITRO POWDER"
I am not aware of Parker pressure data c. 1900, but the Parker Service and Proof Load table was published in the 1930s and reproduced in the
The Parker Story p. 515. 12g 2 3/4” shell Service Pressure is 10,500 psi. Definitive proof used 7.53 Drams Black Powder and 2 oz. shot with a pressure of 15,900 psi. The pressure was no doubt measured using LUP and modern transducer values would be 10-14% higher, or more than
17,500 psi.
LTC Calvin Goddard reported the same numbers in “Army Ordnance”, 1934. He wrote that Parker followed the SAAMI standards of that period: 13,700 psi proof, 9500 psi service for 2 5/8” chamber; 15,900 psi proof, 10,500 psi service for 2 3/4” chamber (by LUP)
+ 10-14% for modern transducer measurement.