I am now using the area 419 bullet comparator and a precision seating die by Redding and still getting a lot of seating variability with my bullets. Should I chase each bullet by seating long and getting as close as possible to my planned seating depth or should I average a bunch, set the die and go from there for the whole load? I can get up to 10 thousand of variability. What are acceptable variances and how to other reloaded deal with this ? It seems crazy to to me after doing a very precise bullet seating ladder. Thank you
Kind of depends upon the specific situation you’re dealing with. If you got your bullets kissing the lands then going just a few thou over can absolutely ruin your day. If that’s the case, then I would personally have a maximum length and everything needs to be completely under that . On the other hand, if you’ve got a good bit of jump then a few long bullets aren’t going to cause you that much grief and an average might be better.
I’ve purchased $100 a box, match grade custom ammo and measured them and found seating depths difference of up to 7 thou. I chatted with one of the comparator manufacturers when I first started and he was saying 5 thou differences were perfectly acceptable to him.
Also need to remember that your typical digital caliper has an accuracy of 0.001 plus or minus, thus an actual difference of up to 0.002. Then you need to add in the accuracy of the actual comparator body, and then add in the human factor of how straight is it, how much pressure, Etc and it’s easy to see how how much variability you’re going to have just based upon actual measurement techniques, sensitivity of the system.
One other thing that I have observed that caused the biggest variability was powder compression. If you’re dealing with a big charge or really seating deep, that plays absolutely Havoc with consistent depth
I honestly wouldn’t worry about 10 thou of variability. I’d consider that very normal and you’ll get phenomenal accuracy if everything else is on.
Thank you both so much
Id check your case prep deburr especially.
Speaking from experience i wasnt deburring equally consistently i coulf feel a bullet dragging as i seated it.
Wow! .010 variation in seating depth with a micrometer die - that’s crazy in my mind. I use a $37 Lee micrometer seating die and I have essentially zero variation. Maybe +/- .001 when I sample a batch of handloads. I double check about 3 at the start of the batch, sample about 10% along the way, and make sure I check the last one. It stays consistent all the way through.
I saw the other responses. Jim is probably right. +/- 5 thou probably won’t matter in the big picture if everything else is good…unless you are right up against the lands as others mentioned. But if you are shooting monolithic copper (or cup & core for that matter), and are .050 - .150 off the lands, it would likely be tolerant of the variation you are seeing. Inconsistent deburring? That would change the force needed to seat the bullet, not the depth itself. And a compressed powder charge? As I understand it, a highly compressed charge would push the bullet out of the case over time, like overnight. But I have not seen that cause immediate seating inconsistency. But I have little experience in that area.
A few questions. Are you finding inconsistency in BTO measurements after seating with the same die setting? Or are you finding inconsistency in COAL measurements? In other words, BTO is consistent from round to round, but COAL measurements are showing the variance?
If the latter, it’s inconsistency in the bullet itself. The ogive-to-tip measurement is inconsistent. I highly doubt that. And if your load is jump sensitive, it’s the distance from ogive to the lands that matters, not COAL.
If the former, I would double/triple check your die set up in the press. I have no experience with your Redding die, but my Lee die needs to be seated in the press so the it totally bottoms out on the press stroke and the press needs to cam over just slightly, putting force on the die. I think it’s called a “dead stop” die and it results in great consistency. I have to believe your higher quality Redding die is capable of the same.
As others mentioned, your variation may not really matter in terms of precision performance. But I assume you, like me, handload for precision/consistency. And .010 of variation is not good enough. So go back to the instructions of setting up your die, watch a youtube video on that topic. Would love to hear back from you.
Jeff