What probe is he talking about. A probe is something you fill your gun with air right?
I get how it works now. What I don't get is the desire to do it. Basically you just avoid having to mess with breech screw, and that's the only possible justification for doing the mod, but I really dint think it's worth the hassle. I've taken that little breech screw out dozens of times without a problem.
Apparently someone, sometime, suggested that if you put a HiPAC into a 22xx and didn't drill and tap for a couple of proper screws to secure the valve into the main tube, the valve might come flying out the back of the cylinder with 3,000psi behind it.
There is a sticky on another forum about this. If that is what you are referring too, then I think that sticky should be taken down. The mods detailed there in no way secure the valve. The OP talks about securing the end cap in case of failure. Securing the end cap won't prevent failure. A failure means a trashed pistol. Yes, it may contain the valve if the screw shears, but its still a trashed gun and is still dangerous.