GBBP Piston Head O-Ring Blowout

[MrAirsoft194]

So i'm having an with the o-ring on the PDI winter piston head poping off the head when I shoot.

It's a KJW P226E2, I got a guarder lightweight housing, stock air nozzle and a PDI winter piston head. I had this setup for more then a year, excluding the housing (that was recent) and it shoot fine until that one day where I needed it, it failed.

I've tried short stroking the travel of the nozzle so it doesn't pass the o-ring, but it still did it. The nozzle itself seems fine, it has a good seal with the o-ring, not loose. At this point i'm at a loss of what is the cause of this and hoping someone here might know a thing or two.

[RainyEyes]

If the o-ring is coming off it means that it is too big/loose for it to properly be seated. You need an o-ring that is tight enough to not get moved out by the slide returning to battery but also big enough to perform an adequate seal.

You can head out to your local princess Auto store and grab a box of o-rings for $20 cad and then a roll of Teflon tape. Use an o-ring that is the same size as the piston diameter and slowly add Teflon tape until it creates an adequate seal. Then add some gbb silicone oil, press down on the o-ring, and add more Teflon tape until the oring makes an adequate seal without it being able to compress due to oil and moisture on the Teflon tape.

The pdi winter gbbp piston head is garbage in general though, notorious for cracking. Better to get a laylax/metal one.