What BAR Presuure is this Proofed?
 

Lincoln Jeffreis, JNR., 120 Steel House Lane. Birmingham
Jeffrie’s Long Range High Velocity for 3 “Brass case 12 bore 3 inch # 3770
Barrel 32”, weight 9 lbs. nitro proof for 1 & ¾ oz
Bore 0.751” right choke .012 and left choke .038
What would be the service pressure?

The gun was originally proved 1925-1954.

It was reproved to CIP standards (the crowned R) after 2005; I can't make out the date thereof.
It carries 12g 76 mm = 3” LEAD "High performance/Superior Proof" (the 2 Crowns over SUP)
Maximum Average (Service) Pressure 1050 BAR = 15,229 psi
Maximum statistical individual pressure 1200 BAR = 17,405 psi
Magnum proof 1320 BAR = 19,145 psi

Drew,
Thanks very much!
Jim