[Retrofire]

Yes, small arms. M1 120mm round would have taken off the balcony at least, even if it grazed the corner...

That must not be the damage caused by the round that peed in Reuter's Wheaties...

[CatoRenasci]

You would certainly be correct if the 120mm round was high explosive. On the othe hand, if the round in the chamber was an armor-piercing sabot round, it could leave such a small hole (and keep right on going through the building like a hot knife through butter). Similarly, a HEAT round, a shaped charge anti-tank round (also a likely candidate for being kept in the chamber of a tank) it could leave such a small entry hole. However, there would be more blast effect with the heat round, I expect. (It's been more than 25 years since I looked at a target we'd fired live heat rounds into)

[Feckless]

"M1 120mm round would have taken off the balcony at least"

A HEAT round would but a Sabot round would not do lots of damage to a wide area.