Originally Posted by ar15barrels
Different brass types will react differently to sizing.
This is due to variations in brass hardness.
Sort some cases by headstamp and size 4-5 of each type at one die setting, then measure them.
See how consistent they are within the same type vs within the whole mixed batch.
If you are running mixed types like me, just size them all so that even the longest cases are getting sized enough and don't worry about the short ones.
Well, I've been trying to control for that, so this last batch was all LC07 with a few LC08s thrown in. Fired only in my ARs, so no surplus machine-gun brass or anything like that.
I realized I haven't been checking how much lube is on each case - pretty much just letting the lube die do its thing. Do you think an excess of lube (e.g. on the first cases after refilling the die) might build up in the size/trim die and prevent later cases from sizing fully?
The problem really seems to be that something is preventing some, but not all, of the cases from getting fully into the size/trim die. . .