It's a jcurt bolt, no o-rings. The bolt fits tight. Tight enough that I had to spend an evening pumping the bolt in the body to wear it enough to be a smoother pump stroke. Tight enough that if I leave the marker in the Arizona sun, the bolt swells enough that it binds the pump stroke...
I have two freshly rebuilt Torpedo's and both of them work the same on this marker, so I've confident it's not a regulator issue.
Tighter fitting paint/barrel match definitely made the blowback worse when she's shooting up in the 320 range.