Speaking of battlemechs...

[raketenjagdpanzer]

this is some dumb fun with back-of-the-envelope calculations I made a few years back...it's based on the one solid piece of evidence of how much damage a Battletech weapon can do. In the Tech Readout 3058 there's a Gauss Rifle (KE penetrator firing railgun) equipped attack helo. The fluff text for it tells us the gun fires a projectile at "mach 2.2"...we'll work outward from there.

Gauss Rifle ammo is 8 shots/ton. If we assume Metric tons that's 125kg/shot.

The M829A1 Long-Rod DU penetrator round used by the M1 weighs 9kg.

"Mach 2.2" = 748m/sec. The energy from a single Gauss rifle impact is (roughly) 35 megajoules.

The Gauss rifle does 15 points of Battletech unit damage. Thus, one point of Battletech damage requires 2.3 megajoules of energy.

Our DU round from the M1's gun hits with 12.25 mJ energy - or about 5 points of damage in Battletech terms. Not too shabby, not at 1+ km range versus the mere 700 m or so range the Gauss rifle can reach...