I am, if anything,
less concerned with weapons over .50 cal.
A 105mm towed howitzer is a weapon singularly unsuited to criminal misuse. It can't really be used for holdups, a bank robbery would be easy to spot as they set the cannon up in the street after unlimbering it, and you can't murder your next door neighbor with it without causing collateral damage to your own house and waking up half the neighborhood.
If someone has the money and land necessary to actually shoot one of these things, more power to them.