57mm / What type of metal do we have here?

[DEADLINE222]

I assume this is a US, 57mm M70.

Aside from that, I tried to weld a steel rotating band to it today, and the weld immediatley brooke of from the projectile as soon as I applied preasure to the steel bar that would become the rotating band.

Is this some type of pot metal?

 

[Falcon]

It is very unlikely that a projectile would be pot metal.

Welds between two different types of steel don't always hold. For example if the projectile is hardened and the band was mild steel. I do not know the full explanation of this process, this is just what I have been told by one of the welders at work.