is it coming out fast? you said p*ssing it out; which would suggest so, -I mean, would it empty your bottle and stop you playing a full game or is it just a hiss
Does the gauge show input or output pressure to the reg? If its input I would say its just the guage is faulty. If its output The check the reg is the most likey suspect as it looks like it put to much pressure through and blew the guage.
Do they have regulators or gas-thrus? Most Co2 markers I've used have been the latter.
You should be able to replace the guage or cap off the hole no probs.