Well as a rule of thumb safety margins were sometime cited as: Light(Approx 75mm-100mm) 50meters Medium(Approx 100-130mm) 100metres Heavy (Approx 150mm) 200metres. Half that and you get the effective blast radius. But this is not comparable artillery to disperersable munitions. They are feraaly effective in the target area, but at the same time so light that their "blast radius" is comparadle to hand grenade.

The blast radius isn't the problem; it's the shrapnel radius which includes casing and secondary projectiles. For centuries artillery have tried to fire on hard ground to maximize this. Air burst is still the most dangerous. There are three sets of rules for infantry conduct: close barrage training (zero casualties), "battle innoculation" training (1% casualties) and close barrage in action (stay as close as you can). 81mm mortar = 75m, 50m, <30m 105mm ground burst = 100m, 75m, <30m 155mm ground burst = 150m, 100m, <50m For airburst, the rule of thumb is to assume the next highest safety margin. Ground conditions matter - very soft ground is preferred for close barrage because the following infantry can get really close. Any casualties you have from the barrage will be offset by facing the enemy at <30-50m rather than at 75-100m.

Heh interesting note on 16 inch shells, okay so its overkill, but anyways, while these types of shells are more designed to penetrate hard targets, they have a huge lethal radius, anything within 150 yards of the shell burst is dead from concussion alone, they create a crater well over 30 ft in diameter and I believe 20-25 ft deep (although these numbers might even be on the smaller side). Past concussion blast radius anyone standing has an extremely good chance of going blind or deaf or even cause temporary insanity. None of this even counts the shrapnel coverage area.

I have seen a photo of a Tiger on its side in Normandy 1944. A Tiger regiment had been laagered in Normandy when targetted by 16" guns form the battlesips offshore. This one hadn't been hit, but had been overturned by blast. In the accompanying text, it referred to another of the Tigers having its turret blown off.

Artillery scares the out of me. Anything that can bring down that much death from that far away scares the bejeezus out of me

You've got the general idea!