can someone explain or link to how gas pistons in AR-15's work?

[AngryDragon]

sorry for what is probably a newbie question, but i've searched to no avail. i'm most curious in the gas block/piston setup and how that works. i've read that these lead to less maintenance and smoother operation but i'm interested in understanding.

 

[Skald]

History of the Gas Piston system.

 

[Reptile]

http://www.lwrifles.com/tech.php


Animation made by LWRC.

 

[vellnueve]

Basically, instead of the gas tube shooting the hot gases into your bolt carrier key and pushing it back just by the force of the gas (thus throwing debris/gas into your upper receiver and bolt carrier group, possibly causing fouling), the gas is instead used to drive a piston, which prevents the gas from getting free into the receiver by instead using the piston to strike the bolt carrier, forcing it back.

Unnecessary waste of money IMO.

 

[Mike-Mike]

now I want one! It also looks like you might end up with a dirty sight.