The G17 Gen 5 that EyeGuy ordered came in today, so I'll kind of give my run down on what I can see internally and how it feels (point of aim and trigger) really quick along with my general impression.
Internally, it looks like the locking block is held in with the trigger (fulcrum piece) pin. Due to this, the barrel lock up from the Gen 4 to the Gen 5 is different, and the recoil spring based on what I can tell between my Gen 4 and the Gen 5 we got in store, is actually longer on the Gen 5. This of course means that on the G17 at least, that you won't be able to take any current aftermarket barrels and swap them in because the locking block and lugs are further rearward now. The cruciform is slightly differs from a Gen 4, more similar to the G43 in design. Additionally, the takedown tab piece spring has gone to a coil spring from a leaf style spring. The safety plunger, as we have noted earlier, is different and provides a different feel in that it feels less spongy and more crisp. Where you would probably see a little wobble in the front sight it's pretty much gone. Barrel is what's been said with a recesssed crown style, which is interesting and a feature, but I'm not sure that it's land and grove style or still polygonal.
Now, the slide release is thicker/sticks out slightly more than the older releases. But it is ambidextrous, and you can switch the mag release. So left handed shooters have an easier time now. However, with that said, the issue is that with the slide releases being thicker slightly I do not know how that will impact holster fit. So your mileage may vary there.
Externally, the ndlc finish makes it look quite a bit darker and it feels smoother to the touch as well. The mag base pads stick out a bit further coupled with the cut in the grip are easier to strip out if needed, which if you've ever had to do with a Gen 3 or 4 isn't really hard but it's annoying. Orange followers are now present on the mags, which is a nice touch. Finger groves are gone, and that's nice but it's something I could take or leave. I do find that it points a little more natural, which might have to do with no finger groves, but I can't say definitively. Sights are still Glock's trademark plastic ones, but the front dot is bigger, and the rear cup has a larger cut/aperture to view through. The melted/shaved slide on the front is nice and will probably be felt most when reholstering. One thing that bugs me is tht it's only the slide and the frame is still squared off on the front end. Back straps are the same as the Gen 4's that have been offered with the flat back or the beaver tail style.
Overall, the Gen 5 is probably what the Gen 4's should have been out of the box but it does reflect to me that Glock has heard the customer base to some degree. Personally I'm not planning on trading my Gen 4 17 or Gen 3 19 I have set aside in on for a Gen 5 at the moment. Like I said earlier in the thread, if I do get a Gen 5, it's going to be a 19. I think Glock is trying to capture the people that didn't want finger groves, so if you have a Gen 4 or Gen 3 that you're happy with, this is probably not something you will be going out to look for. If you have wanted a Glock, but wanted it without finger groves and didn't want to send it out and have a bunch of custom work done, the Gen 5 is something you're going to want to consider.
As far as aftermarket support, I'm not sure how that will be effected since internally it is different from the Gen 3 and 4's. Especially since how the locking block and barrel are different. I suspect it will be quick to follow on.
