Headstamp Identification

[Bruce_in_Oz]

Yep, Portuguese.

Blasted off a heap of that in the 1980s. Being a tightwad, I went to reload it.

Your basic Brit / Oz / Indian /Commonwealth "large" copper Berdan is 0.250" diameter, (RWS 6000, if you can get them).

The Portuguese stuff is Berdan primed, Jim, but not as we know it. The primer appears to be an odd size, close to the one used in Russian 7.62 x 54 and some European big-bore metallic cartridges. (RWS 5607, 0.254" dia.). Anyway, the Portuguese stuff I deprimed had a VERY large anvil formed into the primer pocket. The traditional Berdan pocket has two dinky flash-holes adjacent to the anvil, The Portuguese stuff is a bit more interesting. There is a very large anvil which has a slot cut across the centre and a single tiny central flash-hole.

If the primer cup on that Poruguese cartridge is brass, not copper, the priming compound is probably lead based, not mercuric based like Commonwealth stuff. Mercury attacks the crystal structure of brass by bonding with the zinc in the brass and thus destroying the structural integrity of the original alloy. We "economy" shooters learned this lesson quickly when trying to reload buckets of MF and RG .303 cases more than once. Thus, the only way to safely contain it is in a pure copper cup. The traditional Mercuric Fulminate / Potassium Chlorate primer was much more reliable in climatic extremes than the early lead based ones, and the original "end-users" were not concerned with reloaders' issues like case life. The mercury buggers up the brass, the chlorate salt residue is what will eat your barrel overnight if you don't clean it out. As per the original instructions, boiling water does this very well as chlorate salts are pretty much infinitely soluble in water.

Note that the aforementioned RWS 6000 primer has a brass cup and is therefore a Lead based primer. It also has something other than the traditional Chlorate for brissance, and is much the same as any modern commercial primer as regards cleaning.