Seating Depth Variances

[Rerun7]

I primarily load SMKs in multiple calibers but commonly get variances of up to .002 when measuring from the ogive of the bullet after loading rounds. I'll have several be exact then one suddenly is off +/-. I'm guessing this is due to slight variances in the bullets themselves or potentially primers that aren't seated as deeply. I use a Lee press and Forster bench rest dies. I've never done any testing to find out how big of a difference this really is to overall performance but it drives my OCD crazy!

Interested to hear thoughts on the effects and causes or variances in seating depths. Is this pretty common and does it really even make a noticeable difference down range?

 

[ALShooter]

Usually neck tension is the cause if primers are all correctly seated and you've measured the bullets to check for variation and find none.

 

[Rerun7]

So do you guys even worry about that much variance or does it not make enough difference on paper to bother with?

 

[prcomte]

The max I'll let by is .002. Neck tension is the main issue when it comes to seating depth. I like the forester dies and I use their seating dies for all my calibers. Though I do polish the outside of the seating stem so it slides much easier inside the body of the die. I've found that it helps a lot with consistent seating depth and seating 'feel'.


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[MTyotehunter]

If they very more than a couple thousandths you may start to see some vertical dispersion, even at 100 yards. .002 probably won't be an issue

 

[idahoorion]

Rerun, I have some loads that were very jump tolerant in testing. Like .020 to .030 all shot the same. Do your testing and if this is so it makes the loading much easier. this is similar to a powder node that is very wide. Some bullets are known for being very specific in where they want to shoot well, others can have some flexibility, Berger VLD is usually an example of the former, and the hybrid the latter.
Smk's have not been critical for me but......and yes, sorting bullets by bearing surface or length to ogive is done. er but not by me hahaha

Idahoorion

 

[Rerun7]

Rerun, I have some loads that were very jump tolerant in testing. Like .020 to .030 all shot the same. Do your testing and if this is so it makes the loading much easier. this is similar to a powder node that is very wide. Some bullets are known for being very specific in where they want to shoot well, others can have some flexibility, Berger VLD is usually an example of the former, and the hybrid the latter.
Smk's have not been critical for me but......and yes, sorting bullets by bearing surface or length to ogive is done. er but not by me hahaha

Idahoorion

Thats a good point, that I didn't think about. I have my data from working the loads up and can see how much variance I had when adjusting seating depth. Did not even think about that.