RT or tank problem?

[10-brink]

Hey, I got RT ULE mag a couple of weeks ago, but I only got to shoot it today. It shot a couple of shots and then stopped. I have no Idea what the problem is. The store I bought it from said it was brand new, so I'm thinking it might have something to do with my tank. Everytime I shoot, the gauge goes from 800 to about 500, sometimes slowly, most of the time it goes back and forth pretty fast. Is this normal?

[Andrew Cunje]

you need an input pressure of about 850 a little less is ok, but the higher u go the faster and more bounce u will get

500 psi input pressure is unsuitable for an xvalved mag

[ilovemags2]

soulnds like yout tank has a bad reg

[10-brink]

thats what I'm thinkin

[10-brink]

anyone got any ideas?