Seating question

[tackleberry95]

So I have recently gotten back into reloading. Previously I had only been loading for medium calibers for deer at closer distance 200-300 yards and in and also varmints where volume loading was the game. At the time we, my dad (who started loading back with his dad back in the 50's and 60's) utilized finding lands by seating bullet until lands no longer visible on bullet then going off COAL. This was always sufficient and we had good luck with groupings with factory guns.

Now that I have started back in and with a 300 PRC, I found the CBTO tool to make great sense along with the modified case to have a more clear view of measurements.

I have the normal Hornady dies for the 300 and while seating pills I check each one for consistency of CBTO. Where I'm finding a bit of inconsistency is I'll get seating die set by sneaking up on the desired depth then I will be .004-.006 off on a few after but then back to original if I don't change anything.

Am I seeing inconsistency in individual bullets as I had only just pulled from the box and not sorted them prior ( what I'm leaning towards)? Am I seeing and inconsistency in the press or the die? I don't have a VLD stem or micrometer stem in the die if this may be a cause. I have seen it through several different bullets that I have tried so far. 212 ELDX, 225 ELDM, 230 OTM Tac.,

Logic would seem, consistent jump would be most important, and to dial for it seating each bullet.

Thanks for any insights or thoughts in advance.

 

[Eric H]

Quickest way to check the bullets is base of bullet to ogive and you probably will see quite a few different measurements. I've noticed that even with some of the ELDM bullets.

 

[Salmonhead]

Bullets themselves are not perfect. Some are better than others. Measuring some individual bullets with a comparator will shed some light on that. Additionally, seating pressure can change and alter your seat depth. I see it often on annealed cases that have not been polished clean.
Besides all that, when you are really close to the lands like you mentioned, every little difference seems to get magnified. Try seating in the zone off the lands somewhere in the .030+ range. I often find a much wider sweet spot with accuracy well off the lands. Certain bullets do better in general at certain seat depths, but generally speaking in my experience, you will do well getting off the lands further. Side bonus is an increased throat life in the barrel if you are off a bit more.
I don't look for seating depth adjustments by the .001" or .003" increments because the bullets often have that much variation in them. I jump .010" while looking for the best depth. Measuring methods can vary a few thou also.
I believe Barnes suggests .040" jumps to look for improved accuracy.
Food for thought. Let us know how you end up.

 

[Pdyson]

You are most likely seating off the point which is not as accurate as the ogive. Take the seating stem out and see how the bullet fits into it by feel to be sure. You'll find it rocks back and forth. The easy fix is to buy a VLD stem for your seater die

 

[nksmfamjp]

Yes, check your stem fit to bullet. It should not wobble.

Also, bullets are made from bullet dies. Often several dies feed a boxing line, so you can get multiple base to ogive measurements within a single lot. Not a big deal for hunting accuracy usually.

 

[tackleberry95]

Did a small check of 20 or so of the remaining box on 225 eldm's and I had .001 to .004 off the rando I pulled and zeroed for bullet base to ogive. That would be the variance I'm probably seeing. Culling a box and sorting I would have to say would and will be the least desirable part of the process. LOL

 

[GLTaylor]

Or, you can get some Hammer bullets
They are cnc lathe turned to .0005 consistency in all aspects. I haven't had to sort bullets in a long time.
Wish they'd been around back when I shot benchrest!

 

[Eric H]

Or, you can get some Hammer bullets
They are cnc lathe turned to .0005 consistency in all aspects. I haven't had to sort bullets in a long time.
Wish they'd been around back when I shot benchrest!

I love the Hammer bullets but after this post I checked some of the .264 124Gr and some were off just a tad. Not much but just a tad .0015 to .003. That's really unnoticeable when seating in .01 increments. Try it with some SSTs and you'll get a big surprise.

 

[tackleberry95]

Or, you can get some Hammer bullets
They are cnc lathe turned to .0005 consistency in all aspects. I haven't had to sort bullets in a long time.
Wish they'd been around back when I shot benchrest!

I do actually have two sample packs to get around to. 199's and 214's I'm interested to see how they do.

 

[Eric H]

I do actually have two sample packs to get around to. 199's and 214's I'm interested to see how they do.

Just picked 10 of the 124gr Hammers to try and prove a load for my 6.5x284. Will get out to the range sometime this week I hope.

 

[spladi]

Different amounts of neck tension ( neck wall thickness) will cause different amounts of brass spring back after seating and variances in cbto measurements. Any amount of bullet\case lube in the neck or on the bullet or not, will give differences. ,004-to-.006-inch variables are a lot.

 

[QuietTexan]

Has anyone thought about if they're seeing inconsistency in their CBTO tools? The aluminum inserts from Hornady don't exactly measure out the best, you can pin gauge them and they vary by more than the bullets do....

 

[Pdyson]

Doesn't really matter because it's only a reference. That's why it's called a comparator. It will only accurately reflect
The difference between two cartridge lengths for your gun. The Actual CBTO measurement will be at least a little different if you use another set, say one from short action customs.

 

[QuietTexan]

True in general, but have you every checked the consistency of one single insert? Measure the same exact bullet ten times with a Hornady vs a SAC. If the Hornady records a range on the same bullet..... you have to apply a tolerance spec to the CBTO measurement you get from it. It the range is 0.001", how can you say that a 0.001" variance in seating depth is real and not in the measuring tool? The measurement can't be more precise than the measuring system is capable of measuring accurately. A common mistake is that if the tool reads to 0.000xx" then the measurement is actually that precise. The measurement is only as accurate as the tool, false precision is the problem. The Hornady tool might only be precise to 0.002", and falsely precise measurements that vary by 0.001" are a finer resolution than the tool can accurately measure. The oblong hole can cant the bullet base, which results in an error that's the cosine of the angle induced by the hole being out of round.

Have you done it? I have, and the Hornady tool reads different on the same bullet in subsequent measurements Because there's a compounding error based on the roundness of the hole in the comparator. Put in bullet, rotate bullet, different measurements.

Have you ever compared two calipers against each other? Another interesting exercise, because of compounding linear error there also.

There's a difference in a $30 dial caliper with a Hornady insert and a $200 Mitu with a SAC insert - namely, repeatability.