It's a full auto conversion part. The stock part is just a flat plate.
Couple of videos here: Les Jones: Full Auto Glock
You can see the conversion block sticking out the back of the slide.
thank you..
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Quote:
"A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise and independence to the mind. Games played with the ball, and others of that nature, are too violent for the body and stamp no character on the mind. Let your gun therefore be your constant companion of your walks." Thomas Jefferson
I was shooting my G19 for the first time, was holding it with my right hand and had my left thumb on that thing! then Ouch! :-) This is how I found out how the damn thing works, by thumb's on experience.
"A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise and independence to the mind. Games played with the ball, and others of that nature, are too violent for the body and stamp no character on the mind. Let your gun therefore be your constant companion of your walks." Thomas Jefferson