Take a nylon brush and some powder solvent like
*Hoppe's No. 9
*Break-free CLP
*Gun Scrubber
etc...
Place some solvent on the part and brush it like you were brushing your teeth. The majority of the fouling will come off. Cleaning every part until it is 100% clean is referred to as "White glove" gleaning. It is unnecessary.
Its a glock....clean it a little, lube it, slap it together and go enjoy it : )
This may help...
http://www.youtube.com/watch?v=_3TdaCGcmn0