Seating Depth Inconsistency

[ReRun]

Need some thoughts on this. I tried searching the interwebs but didn't come up with much.

I'm reloading 168gr SMKs for my .308 and regularly get inconsistent seating depths. 80% fall within an acceptable range (+\-.003) but the other 20% typically run long up to almost .01. I usually end up going back and reseating these deeper to make them consistent but due to the various depths its very time consuming.

Have you guys run into this? What are some of the possible issues? I'm not sorting bullets, do SMKs have that much variance at the ogive?

Additional info:

Measuring from ogive not tip
Lee single stage double piston press
Forester bench rest dies

[CrazyFingers]

Check to see if there a difference in length between the projectiles that seat long and the ones that seat within your acceptable OAL.

[Airhasz]

Are you trimming all your brass to exact same size? Not sure if this will solve your problem, maybe someone else will chime in...

[ReRun]

I usually trim once they reach near the max length so some may be a little inconsistent. If the ram is fully pushed down I didn't think it would matter. I just trimmed a batch last night though so a great time to test that theory.

[Coal Dragger]

Could be the projectiles themselves giving the variance, or it could be your press giving inconsistent ram travel. Is there a lot of slop in the press mechanism where the handle moves? Can you wobble it side to side? Those tiny variances in the amount of actuation on the ram could be giving you your seating depth issues if the bullets are not to blame.

Either way, I would shoot them and see what they do before getting worked up over it. If they shoot well, then who cares?

[Boxerglocker]

Being your are measuring off the ogive. The only physical limitation that could truly account for your issue are:

1. Seating die loose and/or insert dirty. When you adjust your seating die make your final adjustment turn out the insert, that will remove slop out of the threads.
2. If your using a comparator to measure off the ogive and digital calipers, check your batteries. Re-zero often.
3. It's also possible that your lee press has just worn to a point at the pivots that there is play.

[T2C]

Being your are measuring off the ogive. The only physical limitation that could truly account for your issue are:

1. Seating die loose and/or insert dirty. When you adjust your seating die make your final adjustment turn out the insert, that will remove slop out of the threads.
2. If your using a comparator to measure off the ogive and digital calipers, check your batteries. Re-zero often.
3. It's also possible that your lee press has just worn to a point at the pivots that there is play.

This is sound advice. I have found that bullets that are not the same length will have the same C.O.L. measurement at the ogive when loaded into cartridges.

[markm]

Are you noticing any velocity swings, Larger Std Devs, or Accuracy issues?

I've not yet tortured myself with checking seating consistency. I'm resisting this with all my heart.:p

[ReRun]

I don't currently have access to a chrono so not sure about the diff in velocity swings.

The press is tight, I haven't loaded a ton with it (few hundred rounds). Ill check on the die being dirty, I've never cleaned it.

Typically I've gone back and reseated longer rounds or grouped them together so I can keep them separated. I also use a dial caliper and periodically rezero during my reloading sessions to ensure its still on.

Heading back out tomorrow so ill do some accuracy testing to see how it really effects grouping. I've always assumed it would be noticeable due to there being .01 difference on some rounds. Good idea to do a more controlled comparison to see how much difference really before I go to retooling stuff.

Was hoping it may be something common and easy to remedy that others have run into.

[CC556]

Where are you measuring? Meplat inconsistencies can easily account for the variance you're seeing if you're measuring to the tip.

[ReRun]

Ok, so problem solved. Not sure exactly what part did it but I cleaned the die and then completely broke it down and set it up from scratch. I ended up getting a +\- .002 variation which I don't think will make any difference in accuracy. It didn't really seem that dirty so maybe something was loose? Not sure but it works. :cool:

Thanks for the advice.

[Coal Dragger]

Good deal.

[T2C]

It could have been dirt in the die. It happens.

If you don't have a chronograph, I would not get too worked up over it at the moment. I have carefully loaded and chronographed reloads over the years that did not shoot with a darn. I have also loaded rounds that had a wide extreme spread and standard deviation in muzzle velocity and shot great groups. As long as you are not seeing signs of excessive pressure, following recommendations in a reloading manual will get you by.

A chronograph is handy when you want to measure muzzle velocity to calculate bullet trajectory. When you can afford one, it is a good investment.

The acid test is how well your loads shoot on paper at distance. If you come up with an accurate reload recipe, please share it with us.