My girlfriend uses a SIG 2nd gen GSR 1911 as her IDPA gun. It's got over 5,000 rounds through it and has actually been very accurate and reliable after having the original factory extractor replaced by SIG. Last summer, it went off to Grayguns for some improvements. Bruce Gray, who is generally critical of the GSR design overall for several reasons, actually commented to me that this one of the best examples of a GSR he has personally worked on.
A couple of weeks ago, a failure-to-feed problem showed up. It looked like the incoming round was jamming the slide. After working the round loose, though, it turns out the slide itself was hanging up short of battery. I pulled the slide off and found some damage at the back of the frame next to the hammer; there was definitely a rough spot sticking up that could account for the problem.
I posted on SIGforum and Roy, the 1911 guy from Grayguns, recognized this as a gun he had worked on and had me ship it back to him.
I got a call from him where he asked, "So, did you remove the firing pin block on purpose?"
It seems that the screw holding the Series 80 firing pin block in place had worked its way loose, the block had dropped down and impacted the frame, causing the damage, and then had finished falling out entirely.
So, the first lesson for the day is, when people talk about a gun having a particular feature and just giving it "more parts to fail," that's a serious consideration. (I don't consider a Series 80 safety to be a necessary feature; it just happens to be the design of the gun my g/f picked out for herself.)
The second lesson for the day is, when you take your gun apart, really look over it. I focused on the frame issue and never noticed that the firing pin block was missing. I feel kind of stupid about that, although I tell myself that I got the request to ship it back to GGI before I really got in to diagnosing the problem.
Anyway, that's your public service announcement for the day. Carry on.