Re: Data books
I have used the USMC databook, Storm Databook and the Impact Fullsize and Pocket Databooks.
How you use it depends on the type of shooting you do.
You can use it to record the performance of the rifle, ammunition and YOU. If you go so far as to log how you feel on a shooting day you can correlate that to your performance (focused, distracted, in pain, etc.).
A databook is an excellent source for information on how your rifle should shoot if you find yourself shooting in similar conditions again in the future. It's also a great record of your progression of skill.
I also use mine as a training record. If I am ever called out on a shot I made I can use my databook to demonstrate the level that I train to.
I can tell you that both the Impact and Storm modular books are good to go. I prefer the Impact right now due to the way the pages are setup, the cold bore page and the fact that Tony produces pages specifically for our state's qualification course. It will make that record keeping thing a little easier.
However I will tell you that there are days I get lazy and don't log anything other than writing on the shot targets. This is usaully at 100 and in where environmental factors are very minute. If I am doing any long range shooting I log EVERYING.
I will warn you that smaller is not better. I use the pocket databook for my AR10. It's almost too small for my tastes. I am a knuckle dragger and dainty writing is not my forte.
P.S. if you go with either the Storm or the Impact I know where you can get a bitchin' cover.