Good general rules for documenting detonated grenades: do it from the furthest distance that allows for a clear image, treat them as being covered in harmful chemical residue, reposition them with a stick or something if you need to.

Launchers. Launchers come in two calibers, and two styles. 40mm is the modern mil-spec grenade. 37mm is the older caliber, based on flare cartridges. The two styles are single-shot, which breaks open like a shotgun, and multi-shot, which is usually a six-shot revolving cylinder. 40mms will have rifled barrels, 37mms are smoothbore. They can be used to fire a range of different rounds, but the three basic types are gas grenades, muzzle blast and direct-impact.

The gas grenade shells are basically smaller cousins of the hand-thrown ones: pyrotechnic CS. Everything that applies to those, applies to these. They can also cause potentially-fatal injuries. Imagine getting hit in the head with a D-cell battery fired out of a t-shirt cannon. People have been killed by them, and cops aren't very concerned with the "don't fire directly into crowds" rule.

Muzzle blast shells are basically large shells packed with powdered CS, OC (active pepper spray ingredient) or some combination. They fire the powder out into a cloud. Relatively simple, but you don't want to be too close for obvious reasons.

Direct impact is a class of rounds designed to be fired at someone. It can be plastic-coated shot (similar to stingballs), baton rounds, which are solid slugs of wood or plastic, or crushable foam/gel. Some are loaded with OC or CS for extra misery. Generally, they cause large bruises and carry a lot of concussive force. The foam/gel ones are designed to collapse or shatter and attenuate some of the impact, theoretically lessening risk.

So: when you see the launchers come out, you have no idea what they may be about to fire. Be ready for gas, baton rounds, anything. There are a lot of models, but the Combined Systems-branded Penn Arms ones seem to be the most popular in the US. The very large-caliber barrel is the characteristic to look for.

I'll come back to this later with the second half on shotguns and peppperballs, so I'm not completely crowding timelines out.

Okay. Second half, starting with shotguns. 12-gauge shotguns have been a staple less-lethal weapon for a long time in the US. They're just regular pump shotguns, usually Mossberg 500 derivatives. Shotguns designated for less-lethal use are marked with bright orange or green synthetic furniture (the stock and foregrip).

There's a huge variety of 12-gauge less-lethals, but the most popular are plastic-coated pellets (like stingball grenades and launchers mentioned earlier), beanbags and "rubber bullets". Less-lethal shells are often characterized by milky-white, translucent hulls (the plastic part of the shell) rather than the bright, opaque colors of lethal ammo.

The shot is similar to, if not identical to, the shot used in stingball grenades and larger launcher shells. It's aimed and used like regular lethal shot, but produces painful bruises and welts instead. Beanbags are a pouch of lead shot. Older-style ones were square, newer ones are a drag-stabilized tadpole shape that's more accurate. Rubber slugs are solid rubber, or a metal core, with fins on the back like a dart. These are replacing bean bags.

The beanbags and slugs are both direct-impact and they'll produce large bruises. They can break ribs and cause concussions. If you see reports of "rubber bullets", it's probably some sort of 12-gauge rounds being used. As with launchers, be ready for anything.

Pepperball guns are the last thing I'll talk about here. They're basically suped-up paintball guns that shoot OC-filled projectiles. (The first gen of Pepperball-branded guns were rebadged Tippmans with the FPS regulator maxed out.) The FN 303 is the most popular one with US cops. Its nominal FPS rating is 280-300fps and its projectiles are weighted with bismuth shot to make them heavier. It can deliver much more force than a recreational paintball gun.

Pepperball (as in capital-P) is the other major brand of pepperball (in the generic sense) weapons. They make a few models, most of which look and operate like regular paintball guns, with FPS ratings higher than paintball ranges allow. They fire the same .68 caliber projectiles, but they're loaded with OC instead of regular paint. The VKS at the top, which is unnervingly styled like an assault rifle, can also fire rounds similar to the FN 303 projectiles.

As a final note, any of these things can kill you. Even the pepperball guns have at least one death attributed to them. Stay safe out there.