...another total rookie question, but I have been humming right along doing a lot of loading trying to beat Old Man Winter (I am in the garage) and noticed something that raised a flag. My Redding seating die was hitting the locator pin every time at the end of the upstroke. I didn't notice this until I saw one of the little plastic aftermarket locator pin tabs showing some stress. I followed the Redding instructions and installed it to the point where it just touched the shell-plate, then backed it out until the micrometer readings were due West where I could see them. All was well. I've been cranking out some nice ammo (best SD rounded up to "3" in a 10-shot string when load testing and very nice tolerances/results when mass producing practice ammo) with little variance, but the seating die indexing off the locator pin kept weighing on me. I thought...softer than steel, but banging into the pin 100K times can't be good...and thought perhaps it could be holding back another case on the shellplate from fully entering in another die) So I thought no harm, no foul backing the die out a couple turns, so it didn't bottom out on the locator pin. With other dies (sizing, for example) I can see where not getting the case 100% up into the die could be an issue, but with the seating die, I thought a short case would have the bullet seated more shallow than a longer case entering the die. Either way it shouldn't impact OAL at all, just the seating depth based on case length. Now I question my assumptions. I ask, as @9x45 mentioned that the brass wouldn't contribute to the variance I am now seeing in OAL. When I discovered this newfound variance, I measured all my inputs to see what was impacting my output...took 10-20 bullets, measured for size...1 thou variance on 2-3 outliers. I took some new brass and found 4 thou variance. When the die touched the locator pin, I was getting a full stroke still, so barely touching...but is this wrong? I thought so and changed it, then saw some 8 thou variances creep in. I know, I know, and they were fine and shot fine, but now it just calls into question whether my 'fix' for the indexing off the locator pin did more 'harm' than good.