You know what might be interesting to try? Putting a gen 3 slide on a gen 4 frame. I realize the end of the frame of a gen 4 is larger than a gen 3 to accept the larger gen 4 guide rod, but this would just be to see if the gen 4 frame has anything to do with the problem.
I'm pretty sure you can use the gen 3 spring and guide rod in a gen 4 with a gen 3 slide.
IF it can be done, and the erratic ejection went away, it would clearly show the gen 4 frame is not contributing to the problem. Then, once that's established, one could swap all the gen 3 slide parts to the gen 4 slide and see what happens.
Another thought would be put the gen 4 parts in the gen 3 slide and see if the BTF occurs.
Just trying to think of some ways to identify the problem.
BTW, I have two G17 gen 4s, one with 2,675 and the other with 2475 rounds through them and I think I've had one or two BTF and those may have been bounces off the shooting booth wall.
Last edited by Tangle; 10-11-2012 at 06:26..