I was not referring to the common name for the system, I was commenting on G3Kurz statment that the cleanliness of the system is due to the gas piston, which is technically incorrect. That result is due to the oprod instead of a gas tube.
Skip that step - unnecessary as is removing the extractor for each cleaning.
We fired HK416's to 20,000 rounds without ever removing the extractor for cleaning, even during desert testing.
This is one big reasons why the HK416 has an op rod versus gas tube - reduced fouling, less cleaning!
G3Kurz
AGR, I must have missed something, where exactly does G3Kurz make even a reference to the piston? His reference is to the OP-ROD opposed to a gas tube that goes into the bolt carrier group. A solid rod transferring energy to unlock the bolt opposed to a dirty old gas tube. Which, by the way, has very little effect on carbon build up under the extractor.
However, I do agree with you that pushing the pin out and a quick brush under the extractor and bolt cannot hurt anything. Like you, I usually do this too, but not every three months...especially if I have not actually fired the weapon.
Now, as to the original post: replace each time it is removed. I'm calling BS on that, it is a hardened pin, not harmed at all by pushing it out....note: pushing it out as opposed to driving it out, as one would do to a roll pin! This is HK trying to sell LE agencies spare parts!! First time I went to the MP5 Armorer's course, we were told to put the weapon together basically DRY! That went against everything I knew and understood about weapons (or machinery in general for that matter) especially in the humid south. But, break it down, who is telling me to do this? What is their purpose in life, what do the sell? SPARE PARTS!!
Now the roll pins are a different story, they should be replaced, that is a standard in all industry.
Anyway...FIDO