Yes, the issue is that you could bust up the extractor on your Glock, the way we used to bust up extractors on older Star and Astra pistols chambered in 9mm Largo/38 Super when we would shoot the shorter 9mm Luger ammo through them.
Both the 40 S&W and 10mm headspace on the case mouth - the 40 being shorter is only held in place by the extractor and two things could happen - one is that you could bust up the extractor and then you are scrued, as they say. The second is that you could ring your chamber shooting the 40s so that a 10mm would not chamber.
Two recommendations - either load your own snakeshot (say that fast 3 times) into your 10mm cases or purchase 10mm snakeshot, or purchase a 40 S&W barrel to shoot 40 S&W snakeshot.
I'm now wondering if a 410 shotgun wad cup would hold enough shot to be useful against snakes and/or if it would be too big for the bore to accurately take to the rifling and throw the shot accurately. HTH.