I've use a Hornady comparator to measure factory second bullets and found I got repeatable results. Not sure how much they effected accuracy as my lots had a wide range in them so I could group 10 to 20 bullets per lot.
Wonder if any of you old timers from up around Lewiston Idaho remember the old Lolo sports? They used to sell Speer seconds by the pound for dirt cheap. I had about 500 Speer Grand Slam 165 grain 7mm bullets from them that back in the day shot fine but once I started getting more technical with my reloading and stretching the distance I realized that the two to three grain weight variance, different lengths and extra cannular groves in some of the bullets probably aren't helping things. I am using the last of the GS for practice time. I still have a few 1000 of these seconds in various calibers and grain weights I run through my other rifles and I wish I had purchased a ton more back in the day.
As I remember they had the bullets under there counter glass in metal bread pans and would scoop them out into a paper lunch sack for weighting. By the time you got home there would be a hole in the sack and a few bullets would be escaping.
