Will a gen 3 glock slide work on a g4 lower or vice versa? Meaning will my glock 21sf g3 accept a g4 glock 41 slide setup as there was no 41 prior to gen4.
I believe the guide rod/recoil springs are different, on the 19/17/34 anyways. Gen 3 slide can fit on gen 4 frame, will be a gap though in the front on the frame. Aftermarket solutions are available to fill it. It's only cosmetic, to my knowledge.
Gen 4 slide on gen 3 frame require some dremal work on frame to open up area where guide rod installs.
Proceed at your own risk though, I'm not a Gunsmith. Google has plenty more info.