[Azathoth]

The OP was talking about full metal tooth pistons. not metal bodies pistons.

Some gears are absolute crap and the metal teeth on the piston will wear down the gears, instead of it being the other way around. You almost always want the piston to be the point of failure so having your gears wear out because the teeth are too strong is stupid.

Their is a lot of information on the web about full metal teeth pistons, check the date that it was made available and the sources. LOTS of it is horribly out of date. AEGs now a days should be able to run full metal teeth out of the box, Aside from the soft Tokyo marui gears, i dont think you have to worry.

The prometheus hard piston is excellent. It's a 1/2 metal teeth piston. I've run that in extreme FPS setups 550-650FPS. it's one of two choices that are available for high FPS application that is consistently reliable (IE I can get 10,000 rounds out of it).

I don't like azimuth or full aluminum bodied pistons. The side wall deformation ability of the azimuth can be a major weakness. I like the weight in the aluminum pistons. It helps gives the gun a nice crisp sound when paired with a M200+ spring however, again its lack of flexibility in this case is a major source of weakness. I don't need the piston to destroy my gears or chunks of my compression system

Also swiss cheesing pistons probably a bad idea now that the material quality has shot up so much in the last 6 years.