P17 O-ring size/material check.

[JamesD.]

116 or is a 118 an improvement for main piston?

006 x's 2? & a unknown size.

I've read the Blog by DW, but he is murky about that green O-ring and all sizes.

 

[MMCM13]

I ordered the correct metric size from the o-ring store, is was cheap and fast. I used a 2.5 x 20mm o-ring, worked better than the -116 I tried.

 

[JamesD.]

They're metric?

http://anotherairgunblog.blogspot.com/2009/02/derricks-beeman-p17-overhaul-finale.html

That's why I thought SAE. Would you know the other metric ones sizes?

I need to find a good cross reference chart

 

[MMCM13]

This is what I went by. 

https://www.gatewaytoairguns.org/GTA/index.php?topic=164224.0

The reason I was looking was I got an o-ring set from eBay to rebuild a Xisico 120D and the piston o-ring in the kit seemed small, iirc it was a -116 or -117. I ordered rings for the P17s and the 120D I have based on that thread, and velocities are more what I expected. The o-rings from the kit was giving me velocity in the 350 FPS range, the metric 2.5 x 20 is 390 FPS average. 

 

[JamesD.]

Good to know. I'll try both as I have a P17 & the 120D.

Thanks. 
Oh by the way anyone else wondering the 120D is a excellent platform to learn how to crown your barrels and see what a difference that or any mod makes. I'm pretty sure everyone of them needs some love lol.