Seating depth variance/tolerance?

[CharlieNC]

Ogive. I use the Hornady bullet ogive comparator on Frankford Arsenal digital calipers. I check zero and/or rezero the calipers frequently during any reloading session.

My point is you/we do not measure at the location on the bullet where it is contacted during seating, and the bias between them is not consistent. Also try rotating the bullet and reseat using longer dwell time.

 

[Texas Solo]

I have a "node" for seating depth.
Anywhere from .005 off to .020 off makes ZERO difference in my groups. So I load to .010 off and don't worry about the variance.

 

[mgunderson]

Plus and minus the 0.0015 inch is a reasonable tolerance for higher volumes. A good arbor press and a Wilson die will bring that down. I just don't seat enough with a Wilson die to give a better number, but it is clearly better.

 

[TxBowHunter409]

Bullet seating, and the inconsistencies associated with it, is probably the one thing that drives me the most crazy when reloading. I have my case prep pretty much dialed in, but bullet seating has always been sorta hit and miss. And being OCD, it drives me nuts.

I've always used Forster Ultra Micrometer Seating Dies, and they do a pretty good job. The problems I've seen have been total inconsistencies with the methods of actually measuring the seating depth itself. When I first started reloading, I was just using some cheap set of comparators. Those eventually got upgraded to a Hornady set as I started getting better at reloading. Then the Hornady set was upgraded to a set from Short Action Customs. But even those will vary depending on the amount of pressure you apply on your caliper and even whether you spin the brass, or even how many times you turn the brass. So I always felt like I could almost make the reading say whatever I was really wanting it to read unless it was really bad off. This drove me nuts.

Then watched a short video F-Class John did on the Accuracy One bullet seating micrometer. Decided to gamble and buy one. Holy hell.. should have done this in the very beginning. It's at that point that I realized, although there's always going to be slight inconsistencies in bullet seating depths. Most of these inconsistencies are typically not as exaggerated as they appear when using inconsistent equipment to actually take your measurements.

I have found that you're going to come across those occasional pieces of brass that for whatever reason, whether it was not annealed long enough, really needed to be neck turned and wasn't, had too much friction inside the neck itself, or whatever. That regardless of what you do, it's going to just seat dramatically different than every other bullet you've seated. When I come across those casings, I'll mark those and they will get segregated from the rest of the brass.

But if seating inconsistency bothers you, then I highly recommend getting the Accuracy One seating depth comparator. And get the little stand to hold it as well.

 

[JFrank]

The Accuracy one gage has been mentioned a few times today.
I won’t be without mine.

 

[TxBowHunter409]

Bullet seating, and the inconsistencies associated with it, is probably the one thing that drives me the most crazy when reloading. I have my case prep pretty much dialed in, but bullet seating has always been sorta hit and miss. And being OCD, it drives me nuts.

I've always used Forster Ultra Micrometer Seating Dies, and they do a pretty good job. The problems I've seen have been total inconsistencies with the methods of actually measuring the seating depth itself. When I first started reloading, I was just using some cheap set of comparators. Those eventually got upgraded to a Hornady set as I started getting better at reloading. Then the Hornady set was upgraded to a set from Short Action Customs. But even those will vary depending on the amount of pressure you apply on your caliper and even whether you spin the brass, or even how many times you turn the brass. So I always felt like I could almost make the reading say whatever I was really wanting it to read unless it was really bad off. This drove me nuts.

Then watched a short video F-Class John did on the Accuracy One bullet seating micrometer. Decided to gamble and buy one. Holy hell.. should have done this in the very beginning. It's at that point that I realized, although there's always going to be slight inconsistencies in bullet seating depths. Most of these inconsistencies are typically not as exaggerated as they appear when using inconsistent equipment to actually take your measurements.

I have found that you're going to come across those occasional pieces of brass that for whatever reason, whether it was not annealed long enough, really needed to be neck turned and wasn't, had too much friction inside the neck itself, or whatever. That regardless of what you do, it's going to just seat dramatically different than every other bullet you've seated. When I come across those casings, I'll mark those and they will get segregated from the rest of the brass.

But if seating inconsistency bothers you, then I highly recommend getting the Accuracy One seating depth comparator. And get the little stand to hold it as well.

I actually meant to say earlier but got side tracked. I don't use the Forster seating dies and more. I have swapped over to a K&M Arbor Press with L.E. Wilson seating dies.

I'll still use the Forster Ultra Micrometer Seating Dies if I'm like doing seating depth testing on something. But for my normal loads, it's the L.E. Wilson.

 

[Janeau]

No that’s .0015 total.

Like last night I loaded some BRAs and they were 1.7945-1.7955, .001 extreme spread.

The only way I know to do this is a combination of good bullets, good dies, annealing and not wet tumbling. I run a nylon brush in the neck a couple of times right before priming. I want that carbon in there.
If you’re annealing every firing, you might try an Iosso nylon brush in a drill. Don’t get carried away just a couple of zaps on the trigger.

Annealing - sizing - wet tumbling and then applying Neolube inside the neck work perfectly. More consistent than relying on carbon and brush on a drill in my book.
My Borden benchrest gun love my method..brass is shiny - can inspect and see any minuscule flaw if any, and not loading custom bullet on carbon crud is a +.

 

[BringBackThe80s]

If you aren't using an arbor press seater, none of your data would be valid (not to say you didn't).

My guess is that you are crushing your bullets.

What do you mean? What data is only valid if you use an arbor press Seater, and why?

 

[ELR LVR]

How much variation is typical when seating bullets?

I am using 2 Hornady Custom dies with micrometer top and 1 Redding Competition Seater die (also micrometer), all in a Hornady Lock-N-Load Classic press. If I set a seating depth and just load 10 or 25 rounds and only check them with the comparator afterward, then I find variations of 1-3 thousandths plus or minus. (More variation when seating compressed loads, less when there's ample space.) I have found those variations with 4 different .243/6mm bullets and at least 3 different .308 bullets. To deal with the variability, I often back the micrometer off by ~2 thousandths before first seating each bullet, then measure BTO and dial 1 to 4 thou more as needed to seat within a half-thousandth of my intended BTO.

So, how much variation is typical when seating a bunch of rounds without measuring every time a round leaves the die?

I never see more than .001" --- If that
Any variance of +/- .001" is usually only from slight variances/resistance of neck tension
If you look at the profile of the Ogive, the seating stem must contact at the right point of the ogive
---The further down the Ogive the better
If your stem is seating by pushing more against the tip of the bullet this could be why you are seeing variation
Or worse
If the tip is actually making contact which could throw things off as much as .010"
so between the start of the ogive curve, and the tip, the closer to the tip of the bullet your stem makes contact, then the more seat depth variance you will experience.
There are VLD stems you can buy
Or you could drill out the stem to a larger hole dia. (with a lathe so it is concentric)
I think a good dia. hole for your stem would be whatever the hole dia is on your Comparator for that caliber.
You may need to drill your seating stem deeper to make sure the bullet tip has enough clearance to not make contact inside the seating stem. Especially those long sleek VLD's
----------------
You may also lap the hole of the stem with the exact bullet you use most
You ideally want a decent amount of bearing surface when making contact to distribute the force over the bullet, as opposed to making contact with just a ring, which will indent the bullet and deform it
Deforming the bullet by pushing it in on itself will also give variance
-------------------------
I use one of these
The holes in the Hex Comparator are cut with throating reamers
to accurately duplicate the actual throat of a rifle
---I've never felt that complicating something simple, offers better results