Has anyone else bought a gun in the last week? There's that huge terror alert, maybe they are slowing down gun transactions too? I know when my wife flew Saturday security was crazy tight, they rechecked their bags at their connecting flight.
The differences between the gen 3 and gen 4 are the Gen 4 has a deeper, more aggressive hatching on the grip. Too aggressive for my liking as it felt like it was eating my hand after a mag. The Gen 4 has changeable back straps on the grip. Running the middle size makes the gen 3 and gen 4 identical in size and is the size that I would run if I bought a gen 4. And finally, the guide rod was redesigned on the Gen 4. The Gen 4 guide rod will drop right into a gen 3 and my gen 3 27 came from the factory with a gen 4 guide rod. I have no opinion on those although some have had minor issues with them. Every one of those issues that I know of has been a failure to feed and have had no issues after the first 50 rounds or so. In other words, the gun was still being broken in. Personally, there is no reason for me to spend the extra money on a gen 4 when the only difference I would really see (the hatching on the grip) was eating my hand. If you have large or small hands, the gen 4 might be a better fit for you. Only real way to tell is to hold one and see how it fits in your hand. If the gen 3 feels too big or small for your fingers try out a gen 4 with a different sized back strap on there.
Thanks for the info. I watched a video that showed a gen 3 19 being fired then a gen 4. I could see no difference in the muzzle rise so I guess the double recoil spring must help in felt recoil.