Could you be more specific about what part of the gun or regulator was leaking?
It sounds like you're probably just in need of an O-ring and maybe a little grease, both of which you could probably find at your local hardware store tomorrow.
The trick, of course, will be figuring out which O-rings need replacing.
Here's some help with the sizing:
Originally Posted by y0da900
Tail o-rings are 010
Sail o-ring is 20mm OD, 2mm cross sectional, 16mm ID
Bolt bumper o-ring is 015 (014 works fine)
Outer bolt stop o-ring is 018
Inner bolt stop o-ring is 014
Breech o-ring is 017 (behind feedneck, and the SFT o-ring, but the SFT o-ring is typically a 90 durometer)
BOB o-rings are 018, the largest on the back of the BOB insert is 022 (not a required o-ring, just helps it stay snug in the plastic body)