Wonderful inheritance. PE (P = June, E = 1936) probably indicates when the barrel was made. CF3 (C = April, F = 1937, 3 = repair) indicates a repair made to the gun. Unfortunately most all repair records from that era no longer exist.
I hunted Sage Grouse around Craig, Colorado, in 1970.
Sage Grouse near Craig, Colorado, 1970.jpeg
Wonderful area.