When the server restarts, it sets you back to your last login spot.
So if you login with guns, then you die, and then the server restarts (without another login) then you get your guns back. Similarly, if you login with no guns, buy guns, then the server restarts (without another login) then it sets you back to your unarmed state on last login.
Best way:
Buy 'em
Scroll 'em
Relog.
Then you're safe.