Unknown penetrating core

I’ve had these cores for some time now and i am unable to identify what they came from.
The thing about them is that they are very light. below you can see a standard Core from a 20x102 projectile on the left… that weighing close to twice as much as the other 2. does anyone have an idea what they came from and what they could be made of?
Length is 49.31mm for the capped one and 48.65 for the solid.
both are 12.96mm wide.

20200225_134338

thanks already, experiment

The penetrator core on the left is probably made of a tungsten alloy and thus very heavy. The other two (middle and right) could be made of hardened steel which is not as heavy as cores made of tungsten.

Brian

We will need measurements and weights to at least try to ID them.

I know the one on the left is tungsten, its size to weight ratio matches my other cores. but these are so incredibly light, im talking maybe the weight of a live .303 mk VIIZ ball

The two others appear to be from TPDS loads. Likely 25x137.