500mg is not a dose people should start at in my opinion. It's a dose you work up to over time through several cycles like jake pointed out.
250-300 is sufficient to make incredible gains for a first cycle,mane then bumping it 50-100 for the next cycle, etc...
And when it comes to UGL versus Pharma, if you have a legit source, they will be identical. All of our sources here are top notch, so that's not a concern at all
(PM me for a price list for Biotech Labs and 10% discount)