I was stunned at how small of a variation can make a huge difference in reliability. My first time out with my 2nd P14, I used reloads that had been working fine in my first P14. In the 2nd one, it seemed like almost every other round jammed. One of the other guys took a look at my ammo, and said "these look a little long". They miked out at 1.25". I changed my reloads to 1.246" and haven't had a single jam since. 4/1000's of an inch!

Haha.. thinking about that... I recall saying in another thread that a deer isn't going to feel the difference of 14/1000's between a "wimpy" .243 Win. and a "Hammer of Thor" .257 Roberts... Maybe those "thousandths" make a big difference after all...