First, please forgive my ignorance. I'm not sure what the difference is between a generation 3 and generation 4 G21 are. All I know is that I have a G21C that I enjoy very much. It is my ccw of choice. I'm not a huge guy, nor obese, and I don't like wearing jackets, baggy shirts, or having untucked shirts. What I will say is that I carry concealed. Yes, sometimes it prints, but I have found that most people don't notice. There have been nights where my wife never knew I was carrying. Most people just aren't looking, and don't care, until they can absolutely recognize it as a gun, which is always when the gun is displayed and no longer in its holster. I couldn't care about being armed tooth and nail. Last I checked, if the problem isn't resolved after a few rounds you either need to learn how to shoot, or you brought the wrong tools to work with you that day. So, anyways, what is the difference between a gen 3 and a gen 4 G21?