I think a can at 100 yards free-standing is totally within reason.

I was bored the other week so decided to have a bit of plinking fun on my permissions. I was using my TX200HC and have never previously shot further than around 50 yards. I paced out 100 yards down a track under the cover of trees and stood a small mineral water bottle up (400ml).

It took me about 4 shots to hit it at 100 yards. After that I could hit it around 2-3 times in every 5. The next week I did the same with my HW80, hit it first time, then managed 2-3 in every 5 again. Both springers are under 12ft/lbs .22 and I was using a 3-9x40. I was zeroed at 30 yards. Not sure what hold-over I was using, but at 9x mag I was putting the bottle only a few mm off the bottom of the image.

I must confess that I was prone, but nonetheless it was fun

I doubt very much I'd have scored many shots from a standing position and didn't even try it, but I'm not used to those distances, so somebody with more skill than me could easily pick off a can from standing fairly consistently I would think, with the right rifle.

It was great fun either way, although there isn't much power left in the pellet by the time it hits home.....I was struggling to make out where I'd hit. A slight indent was about all the [domed] pellet managed.

Obviously you'll need some fairly serious space to plink at these distances and you need to be super aware of any potential safety issues.