Lube could be an issue but lube that swells the orings would usually make them press into the groove better but it may cause an issue but it is less likely.
My second guess would be that the orings are too small for the grooves were they fit. If they were to small then the air would wrap around then then push them towards the bolt and they could then blow out. Do you have an oring kit for the g4? if so check and find one of the right size that fits a little less snug on the bolt so that it will press into the groove better.
Also make sure that the back cap is tightened all the way. I once didn't tighten it all the way (it was about three or so turns out) and what happened was the bolt touched the oring but only half way so it blew out the oring when i gassed it up.
Last edited by stuff21397 : 03-31-2013 at 08:19 PM.