Piston front o-ring ruined - MSR 700 with upgrades

[Mikaris]

Hi all, I have an Ares msr700 which I've upgraded from what was absolute mess of a replica.

It's now got an AA cylinder, m150 spring, and SCW trigger and piston.

Problem I'm having is that the front o-ring on the piston has deteriorated twice now, and I'm not sure why.

I don't think that there's much fps/compression loss but that's probably due to the double o-ring design and I don't have a chrono so can't be 100% sure. See the photos attached.

 

 

This can't be normal for these o-rings to deteriorate like this right?

I'm using wd-40 silicone spray inside the cylinder, and it's not scored at all on the inside or has any debris. I completely cleaned it out and resprayed the silicone spray when I replaced the o ring.

 

thats how far back the piston gets held by the 90deg trigger

 

Theres also scoring on the rubber seal on the rear end of the piston

 

 

I have a feeling perhaps that it's due to the piston moving back farther than the opening of the cylinder as shown in the image above, and then being forced forward fast against the pressure and maybe its catching on the edge of the opening? But i dont believe this explains the scoring on the rear end, and lack of deterioration on the second o ring.

Looking for any explanations and suggestions as to what I can do to stop or limit this. Any more photos required just let me know

 

Thanks in advance!

 

Edited September 28, 2022 by Mikaris