All the info that has been given is valid. Here's some additional advice on the issue of flinching. Everybody flinches to some degree and at some time or other for various reasons. The best way to combat this that I know of is to use the snap caps (already suggested) AND have someone else load your firearm before you shoot it. They can load a live round or a snap cap so you don't know what will happen when you squeeze the trigger. This has always worked for me whenever I thought I was starting to flinch. Here's what happens: if there is a live round, you pull the trigger, and like always flinch or not, but it's hard to tell. If there is a dummy round, man, you really know if you flinched (and feel pretty silly). Continue alternating snap caps and live rounds at the range and practising with the snap caps at home. Sooner or later, you will pull the trigger on the UNKNOWN snap cap, and guess what, NO FLINCH. You will be amazed and feel great! You see, flinching is more of a state of mind. If you fool your brain into thinking there is nothing to pulling the trigger (which is what snap caps will do for you) you will beat the flinch... for a while, at least, but when it comes back, just start all over again.
More on your original question of "Too Much Gun" to follow.