Its been said before, beware the man with one gun he probably knows how to use it really well. There is some truth to that but I believe that to become really good with guns its good to be able to use a wide range of guns and to train with different guns. Every gun handles differently just like every car handles differently. You get in a different car and while the basic controls might be the same as a previous car it handles differently. Some cars you have to press hard on the accelerator to get it to go and some cars you can lightly tap the accelerator and it will go. Also the steering handles differently as does the other controls. A good driver, though, should be able to get into any car and become familiar with it quite quickly. I think its the same with a good gunman, a good gunman should become familiar with a new gun relatively quickly. Even if its the same make and model as a gun you're used to there will be some trace differences in how it handles. One Glock 17 is going to handle differently than another Glock 17. I used to do equestrian and every weekend you would be assigned a different horse. They would say that you become a better rider if you're familiar with many different horses and with horses there is even a bigger difference on how different horses handle than there is with cars or guns. So I do think a good gunman can benefit by training with different guns to some extent, just like with cars and horses.