Type variation on Czech 7.62x25 steel core

I hadn’t ever noticed this variation before, and it may be nothing, but after melting a couple cores out of two different headstamp 7.62x25 cartridges, I retrieved the following two cores which have a distinct difference in shape. They both weigh exactly 41.5gr which leads me to believe that this is not simply a manufacturing oddity, but rather two distinct core types which are nearly identical. Anyone ever notice this before? The two headtsamps were bxn 53 1 (shown at left) and bxn 54 (shown at right)

There is also a variation with a more cylindrical core. I’ll try to post a pic of my cutaways to show it.

I have one of those cylindrical ones without the mushroom shape also, this is just the first time I had noticed a variation in the mushroom version.

With the different cores in Czech 7.62 mm Tokarev bullets goes at least two different length bullets. I do not have any pulled ones anymore to measure the lengths, but Povazske Strojarne. of what is today Slovak Republic, loaded a longer bullet than did Sellier Bellot, of what is now the Czech Republic.

Aside from that, both factories of the former Czechoslovakia loaded both GMCS and CNCS bullets in the 7.62 x 25 mm cartridge.

So, there are more variations to the Czechoslovakian 7.62 x 25 rounds than, literally, meets the eye.