That would be 1954 (H=1954). The military bought a lot of .22 Match ammunition for service teams, etc. I was on the Navy ROTC rifle team when I was in college, and I fired a ton of the Western Super Match ammunition.

Still remember the Marine Gunnery Sgt who ran the team. We would go in to practice twice a week, and Gunny would give each of us a 1 lb coffee can of loose ammunition, maybe five boxes. And we stayed until we shot it all. We used Winchester Model 52Bs. It could be boring, but at least I didn't have to buy the ammo myself.