to answer your question esldude yes, it is a combination of his practice and probably his inate skill. of course everyone skill level and the drive to hone that skill will be different. if your trying to get everyone up to a certain standard then it is obvious all your time spent with one gun will prove better than trying to train people with multiple weapons. i take this question on a more advanced level( i dont consider myself an expert). like someone who shoots freq about 3000-5000 rounds and is trying to hone his skill above the average shooter. say they only shoot 4-5 times a year . maybe 100-200 rounds. I am sorry i dont own winchester it would help my pocket book alot. as mentioned before you can make certain conditions for each that would sway the way one thinks but in a big over all picture. perfect practice makes perfect so divide up your time. at some point you will reach your maximum proficiency with out additional training. point of diminishing returns. so if you put that additional time in another weapon. why would you say you cannot be well versed in multiple guns? thats my question to you.