Brad, there are no dumb questions - it's only dumb when you fail to ask and get yourself in trouble due to pride!

Many Match handloaders tailor there accuracy loads to the individual chamber by seating the bullet to the "most accurate" length. You would want to be pretty advanced in your handloading knowledge and practice before you attempt this, and special tooling is recommended.

I suggest you read up on the subject extensively and talk to some advanced loaders, but until you feel competent, stick with the specs in the Handloading Manuals. (Also, an AR has a maximum length due to the magazine itself to consider.) Get ahold of Zeddiker's (sp?) book "The Competitive AR15" and give it a read - it will explain. Cheers, CC.