Just found out, why the cylinder of my 586 sometimes didn´t close as smooth as usual while shooting the Infinity Euro Open. 
The reason was a broken firing pin! Luckily, the breakage was at a point, where the rest of the pin was a little bit thicker than the firing pin hole so it stayed in position and ignition was possible!
But now the best: I´ve written a mail to Randy Lee of Apex Tactical (www.apextactical.com) immediately, telling the problem. I´ve just wanted to order some new pins. And guess what wrote Randy to me? New Pins will be on their way to me right on tuesday as a replacement!! This is what I call a perfect customer service!