Having troubles with seating depth...

[cwuwildcat]

Consistency can explain a little as well.  Make sure your pull is the same every time.  If you're distracted, got the radio on, wife walks in, etc... your pull may vary enough.

[GregMcFadden]

1-3 mils is down in the range that can easily be caused by sloppy calipers or inconsistent form when using them as well...

[grundy53]

1-3 mils is down in the range that can easily be caused by sloppy calipers or inconsistent form when using them as well...

How much will this affect accuracy?