i bought some strings today for my p-bass, but i'm unsure as which which gauge to use without damaging the bass since the guy in the shop said if the bass isn't set up for it, a too high a gauge can damage it. i got some ernie ball super slinky roundwound strings with 45-100 gauge if that's any help and i like playing hard rock and power metal. thanks in advance
Those'll be fine, but for the genres that you enjoy playing, I would recommend that you up the gauge on the A and E strings.
yeah dude, they'll be fine. they're the standard gauge for bass strings, so if your saddle wont hold them in place, there's something wrong the saddle, not the strings
so it doesn't entirely matter which gauage i pick then?
It does. If you pick too thick or too thin of a gauge, than they'll not fit the nut and will not stay put on the saddle. The gauge you have is, like Low_End said, pretty standard, but, IMO is a little too thin. I like some girth under my fingers. But, it's your choice, and your choice is fine. You have no need to worry.
Most of the time gauges within .20 or .25 of the standard gauge (.45-.105) will fit in the bridge and the nut. I know my bass can handle all of the strings with gauges of the string above (i.e. the B slot has an E string so .130 to a .105). Other than that, the change in gauge really only requires a change in setup. Probably a small adjustment to the truss rod and maybe an action change and then finally intonation. If it's only .05 or .10 gauge difference the changes will be quite small. No string gauge change, within reason, will actually "damage" a bass.
I think 0.045 G strings are a waste of time I prefer 0.055 for the extra punch and power that they give, this is just a personal thing although as I've said before on this forum the standard gauge for Fender G strings in the 60s was 0.054.