rock salt: Lethal or not

When I was a young boy I used to spend a lot of time at my grandma's place out in the country, her backyard bordered on a corn field. The farmer that owned the land was well known to load up rock salt in a shotgun and fire it in the direction of all us young juvenile delinquents who trespassed in his fields...
If you load one with rock salt, the second with peppercorn, and the third with birdshot, you should be able to bring down a bird and season it in the field.

It’s probably most useful used As a filler to make back pressure on the wad and shot in the air as a blank to scare off roving critters. I would think something less corrosive would be better. Particularly for a shotgun you’re likely to pick up at night and not want to clean right away.
Salt is irregularly shaped and much less dense than metal shot. These two factors cause it to (a) disperse rapidly (b) not have much momentum when it leaves the gun and (c) lose velocity rapidly through air resistance. All of this is to say that lethality is very much a function of distance. 10 feet from the muzzle it’s probably deadly. 20 yards from the muzzle it’s probably not.

Buy some heavy mylar balloons and shoot your salt loads at them from a distance. See how close you have to get before you pop the balloon. That’s probably somewhat equivalent of how close you would need to be to rupture an eyeball.
Salt in my shotgun barrel? Nossir. Not my gun.
Not agreeing, nor disagreeing with you, but wouldn't the wad protect the barrel like it does for other types of shot............?
Also, they are our guns and we could/can do whatever we like with them, so again, I'm not calling anyone out, simply asking a question............ :)
Salt in my gun barrel? I shoot a Mosin with Russian military surplus ammo & shoot blackpowder and BP substitutes. I often clean like there's salt in my gun barrel. So not a big point to me.

When I experimented with rock salt in 12ga shells I used BP just to connect to the 19th century. I decided BP blanks would be just as effective as a wildlife deterrent.

Rock salt: Lethal or not. Use of a shotgun is use of a deadly weapon. At point blank range, rock salt and blanks can be lethal. But in RAISING ARIZONA Nicholas Cage was given brownie points by the parole board for deliberately using an unloaded shotgun. So use of less lethal ammo might factor in at sentencing or probation. As usual my hypothetical legal advice is worth every penny you didn't pay for it.
Some of the police, seen in the recent college riots, appear to be firing shotguns in the direction of the miscreants. Those are surely something commercial....any thoughts on what??
Understand the reasons for the OP's question, which don't include two legged varmints.
My problem; we all have been schooled to not point a gun at anything without a really good reason.
I'd have a hard time making that transition, even if the gun was loaded with something, theoretically, 'less than lethal'.
It's certainly part of the reason that our war games blank adapters blocked the muzzle of our M16s, making it mighty sure nothing was getting out of the barrel.
ETA- when teaching our gun safety course, I began the second hour by pulling out a pot-metal 1911, and promptly breaking rules 1, 2, and 3. The students were supposed to critique what I was doing wrong, and they did. It felt really wrong to point the fake gun at the students.
Back on post #11 I mentioned a constable being killed with .22 rat shot. 1 little pellet to the heart was all it took.
Back on post #11 I mentioned a constable being killed with .22 rat shot. 1 little pellet to the heart was all it took.
Shot pellets or .22 bullets that get into the bloodstream almost anywhere in the body may circulate until they block a blood vessel feeding the heart or brain.
That's how the .22 short RG 10 Saturday Night Special got its fearsome reputation in the 1960s.
If I was after just scaring an animal away, I'd probably try a paintball gun, perhaps with 'pepperballs' loaded up. It avoids the whole 'pointing a gun at someone' conundrum, and also has fair range and accuracy with a very, very low chance of lethality.