[Polynikes]

The “switch” defeats the sear on a Glock. It causes a slam fire situation once the trigger is depressed. Think instant mag dump.

Its can be as dangerous to the user as the intended target. The muzzle jumps around but can be controled. Just watch some YT videos.

https://www.youtube.com/watch?v=2WPpHqEfkHM

[Myrddin]

My local range had a Valentine's Day special a few years back. Dinner and full-auto on the range. The full-auto firearm was a Glock 18 with a stock and red dot site. The "special" included a box of 50 rds of 9 mm. My wife and I split the box. I was able to keep all of my rounds on the paper with short bursts. My wife did pretty well putting rounds on the paper. Even with the stock and a decent "forearm", it was an interesting feeling with both muzzle climb AND a twist to the upper right from the rifled barrel. Doing the same with a Glock 17 equipped with a switch would be more difficult to control.