The opposite extreme, I've seen a G&P piston last over 200,000 rounds without breaking! But of course that doesn't mean crap lol
Seen them fail (on average) anywhere from 12,000 to 40,000 rounds. Most common
cause of failure is breaking off first tooth. I think I've only ever seen one get stripped.
Seen two CA pistons, broken out of box. Heard of them lasting anywhere between a mag and 3 years. Typically around one season for average, most common failure being first tooth breaking off.
Marui pistons. Left stock? Indestructible. Most common cause of failure is stripped teeth, in both stock and higher fps. Nylon has excellent shock absorbancy, but because it's not very hard it tends to wear impact grooves which eventually strip it.
my old prometheus piston from my 249, around 180-220,000, survived being half engaged twice too (my own fault playing with the triggermaster settings)
I believe for prommy, they strip. Due to being made of hard POM, the first tooth tends to wear an impact groove that then alters engagement with the next tooth. So removing the second tooth is very beneficial.
new system supercore piston probably up to around 90,000 and still going strong!
Most common point of failure would most likely be the back breaking off, but I'm not sure. Surprisingly VERY durable for a polycarbonate piston, most likely due to it's prometheus style heavily reinforced first tooth.