Canada

In all seriousness though, it's about as stupid/genius as it sounds. Out biggest stumbling block was actually dispersing the firefighting materials. The bullets worked fine, some custom modified ammo we spent a week making. Turns out, you can get rid of 3/4ths of the steel core and still have adequate terminal ballistics to put significant holes in large batteries. Edit: note I'm talking about like. Batteries the size of shipping containers. The kind that pulls up in a truck and powers entire industrial buildings. When one of those catches fire, the standard protocol is literally "run".

The benefits of artillery shells is that you have a significant parabolic arc, which means if you have the shell start venting firefighting chemicals (baking soda) once it drops below like, 50' altitude, you get proper coverage. Bullets, you can't do that without adding secondary explosives. At that point, you just don't have enough payload in a 5.56 to make a meaningful difference, and relying on impact to disperse the chemicals just won't cut it in the case of batteries.

Also I got to expense several rifles on a corporate card. Didn't keep them, not a gun guy myself, but we had both an AR-15 and a .308, both official science guns. Unfortunately, finance folks flagged me when I tried to expense a 50. Apparently, once you try to get anti materiel rifles, they draw the line.

Firefighting artillery is pretty genius though. Sad that Boeing hasn't done anything useful with it.

Edit2: I never answered one of your first questions. Never been shot, and I've got a least one draft dodging charge to prove it.