There are quite a few videos of this on youtube.  I tried it out but couldn’t even get close to clambering a round (snap cap in my case).  I’m skeptical that these guys have factory springs in their guns… at the very least I’d say they would have a VERY “broken in” factory spring.  I haven’t seen anyone do this in real life with a stock glock yet.

Maybe i’m just not quick enough.  Once my shoulder and elbow recovers i’ll give it another try.