Well, I personally bought two of these pistols... The first one had an issue where the mag release wasn't quite in the proper place so fully loaded magazines had to be slapped in WAY too hard and couldn't be taken back out without prying them out hard or racking a round into the chamber to take some of the pressure off the mag spring to lessen the friction on the mag release so the mag could come out. I took that pistol back to the counter and they called the CFO and changed my serial to another GP6, which now belonged to me. When I took this one on the range, I noticed when the slide was racked back, the slide release alone wouldn't release the slide unless you put substantially more pressure downwards on it than necessary (note the first pistol's slide release wasn't like that). I then took that one back to the counter and was put on a list for a third one. That's when I decided to play with the range model a bit more to be sure I really wanted this pistol and that's when the sticking slide issue came up, necessitating application of pressure through the ejection port to "release" the slide from the barrel and allow the slide to travel backwards. A quick field strip and rudimentary cleaning of the channel the lug travels through on the slide fixed the problem, but finding out less than 1000 rds had gone through the pistol had me go back to the counter and cancel my order for the third GP6 entirely. Instead I bought a CZ.
Maybe these were an early batch (they were, in fact, the first batch this store/range received) but the feeling I got was that quality control just wasn't there. They should have spotted the problem with the mag release and the problem with the slide release if they had put the pistol through it's paces before shipping it out.
I'm sorry, but frankly your experience with this gun doesn't suggest anything to me other than you may be a tad too dainty in handling one, and you got a dirty range gun.
Both of mine have worked fine, and your point about the slide stop is almost too funny for words. It's a slide stop, not a slide release. Although many people do thumb them down to release the slide, it's poor form.
Jaroslav designed this gun to release the slide with a sharp insertion of the magazine. It does it 100% of the time. In three years of competition, it's never let me down. If you order from the factory, and prefer the slide to lock open and remain open on mag insertion, they will cut the slide recesses deeper.
The magazine catch is a magazine catch. It holds full magazines tight. That's not a bad thing, unless you can't insert them to full lock. Like any new gun, the mag catch tip and the magazines cut out will work in after a bit.
My K100 was a bit less tolerant of dirt than the GP6, and as a result I switched to VV N320. I don't know what, if any dimentional changes happened from the GP K100 Mark 6 that Target was renting, to the GP6, but the current model just keeps on ticking.
I use a very small amount of grease on the roller cam, the front frame lugs, and that's it. Over oiling the chamber end of this gun could cause caking of fouling, and more problems than the oil would cure.
. 
