Frankford Arsenal report R-1646, DEVELOPMENT OF CASE, CARTRIDGE, ALUMINUM, FAT49E4, dated July 1962, deals with the successful manufacture of a suitable aluminum case for 7.62 x 51 mm cartridges in 1959. In page 13, it can be read:
Inasmuch as the firing results still showed primer area casualties, it was decided to discontinue efforts to modify the case dimensionally or structurally in an attempt to overcome primer area casualties, but rather to go, as a last resort, to the use of the steel adapter cup-type primer which had proved fruitful in eliminating primer area casualties in other sizes of small arms aluminum cartridge cases. A small quantity of Remington #72 primers with copper plated steel adapter cups were available at this arsenal from a prior aluminum case contract.
The report includes drawings of some 7.62 x 51 mm FA T49 cases. The primer pocket diameter in the definitive T49-E4 case was .2295 (5,8 mm), while that in the T49, T49-E1 and T49-E3 cases is .2093 (5,3 mm).
My questions are:
What are “Remington #72 primers with copper plated steel adapter cups”? Primers that Remington made with a reinforcing steel ring around?
Does anybody have a photograph of a case head with one of these primers? I think they should be evident because of the adapter cups and the larger diameter.
I remember to have seen an early production .454 Casull cartridge that had a steel ring around the primer to reinforce it and avoid primer leaks.