SpudFiles

To help convince yourself that the gun is OK to 100 (or 120) PSIG you can hydro-test it.

Fill completely with water then pressurize with air (water would be better for pressurization but most people don't have access to a 100+ PSIG water source).

Let sit, smack it a few times, jiggle it ... in a safe way of course. If it does rupture when filled with water, there is very little energy stored in the gun.

And, any leaks are easy to find.

has anybody tested or know what the pressure rating for orbit sprinkler valve?

The rating is about 125psi if I recall correctly. It wouldn't be much higher or lower then that.

The problem with a sprinkler valves pressure rating is that it is probably the pressure where it starts to leak, not it's (catastrophic) failure pressure.

For potable water systems (i.e., lawn sprinkler systems), things are usually designed for at least 125 PSIG (twice the nominal water supply pressure of ~60 PSIG).