S-Thunder Moscart Shells leaking.

[Hash Vapor]

I bought 2 S-thunder Co2 shells.

I figured they were Co2 rated then they should be fine with propane, after one shot each they now vent gas when I try to fill them. I noticed the Canadian tire silicone spray I bought made the o-rings swell.

I purchased 2 new cores with o-rings, installed them today, and tried to gas up with compressed air first and then propane with new oil but still venting right from the little hole inside.

Any help would be appreciated.