HOW DO I BUY A GOCK 30 GEN 4 ONLINE THINGS TO KNOW BEFORE YOU BUY

I'm undecided when there is Substantially I can perform to further improve on it but, if there is I would like some Concepts from These of you who've modified their pocket tanks. Besides evening sights that's an apparent update with the typical glock sights. Many thanks in advance.Which is based on operator-claimed complications in the sooner G30SF