The only Glock we have now is my wife's 19. I have been taking care of it for her since Nov. of 2004. Its smooth as glass and back in 2012 I resprung the gun and it shoots even better now. Ive had people rack the slide and shoot it and say its the smoothest Glock they have ever had the pleasure of shooting and handling. HOW?????
Every Glock we have gotten Has went like this. Lube it really good out of the box DO NOT REMOVE COPPER COLORED LUBE ON SLIDE. Shoot 500 rounds of various ammo. No problems Change sights to Triicon night sights and shoot another 100.
If no issues completely strip. Then wash ALL plastic parts in dish detergent and water in the sink using old tooth brush (Magazines and all mag parts except springs). Metal parts go into tin to be submerged in Break free for about an hour. Then dry all plastic parts and allow to air dry. Metal parts get scrubbed and cleaned then sprayed with gun scrubber. Then cleaned of that then reoiled and wiped down. Plastic parts get inspected again and then all parts reassembled. Now reassemble slide barrel and frame and lube per manual.
DO the above
once every year if shooting 2500 rounds or more per year. Anymore than 2500 rounds per year then its up to you. Thats 200 rounds per month roughly. Pick a time frame Christmas New years maybe a holiday where you do nothing but eat a lot and pass out, say like thanksgiving. I do it every July 4th because me the wife and son go shooting every year on that day. Makes a good time to strip and clean.
The wife barely shoots the 19 anymore. The last time I was fully taken down was in 2012 when I did the respring and put in a new set of spring cups and channel liner. The gun was filthy she shot probably 4000 rounds through that gun in a year. Since the gun has less than 500 rds. fired through it since 2012.
Those of you you have shot 5000 or 6000 or more rounds through your gun and have never done this. DO it THE SHIT in the gun will amaze you especially the firing pin channel.
DO NOT USE a bore brush in the firing pin channel it can pull out the channel liner and crack or damage it. use q tips and lots of lube.