Bullet seating depth inconsistencies

Drewdemon · Sep 4, 2018

I’m still new to reloading, I’ve done my load development and have reloaded about 400 rounds so far. I've got an issue with a new lot of brass. I've painstakingly tinkered to get my seating die perfect. This worked great for the previous lot of 200. Now, i switched to a different set of brass and my seating depth measured from the ogive is all over the place. I find myself changing my seating die to get as close as i can to my prototype round.

Im not sure how to troubleshoot this? I thought it might be the new lot so I picked 15 bullets and cases, measured them (cases/bullets) so every single one has consistent measurements. Then i seat them but when i measure from the ogive there is large variances.

Prototype Round
Ogive: 2.228
OAL: 2.850
Hornady 6.5 CM Brass
Hornady 140gn ELD-M
Forester Co-ax, Forester micrometer seating die

Lot of 15 ogive measurements;
2.206
2.213
2.220 x2
2.223 x3
2.225
2.226 X2
2.227 x2
2.228 x1
2.230

Any help would be appreciated!

mdmp5 · Sep 4, 2018

You cannot possibly get an exact seating depth from leaving the seating die at one setting. There are minor inconsistencies in any brand of bullet, causing small variances in base to ogive. If you want the same exact measurement, you have to seat the bullet a little long, measure, adjust the seater and set again, then measure to confirm. You need a micrometer die to do this, which you have already, and the forster is a good one.

Mordamer · Sep 4, 2018

A friend and I both had issues with forester's seating stems not fitting correctly on the 140 ELD-M ogive. I had no issues with 2 other bullets I loaded, but the Forester seating stem would stick on the ogive of the 140 ELD and cause inconsistent seating. Often when the press ram was retracted there was a snapping sound of the seating stem popping off the ogive of the bullet. If this sounds like a possible cause in your situation, a fix is to put some polishing compound on the ogive of a bullet, chuck the base end of the bullet in a cordless drill, and run it spinning into the seating stem to polish the seating stem so that it no longer sticks.

Drewdemon · Sep 4, 2018

mijp5 said:
You cannot possibly get an exact seating depth from leaving the seating die at one setting. There are minor inconsistencies in any brand of bullet, causing small variances in base to ogive. If you want the same exact measurement, you have to seat the bullet a little long, measure, adjust the seater and set again, then measure to confirm. You need a micrometer die to do this, which you have already, and the forster is a good one.

What is an acceptable variance? I measured factory 6.5 CM 140G match ammo and the variance is +/- .003 on all of them. Im not sure i'll get the variance that low but what's within normal limits?

Drewdemon · Sep 4, 2018

Mordamer said:
A friend and I both had issues with forester's seating stems not fitting correctly on the 140 ELD-M ogive. I had no issues with 2 other bullets I loaded, but the Forester seating stem would stick on the ogive of the 140 ELD and cause inconsistent seating. Often when the press ram was retracted there was a snapping sound of the seating stem popping off the ogive of the bullet. If this sounds like a possible cause in your situation, a fix is to put some polishing compound on the ogive of a bullet, chuck the base end of the bullet in a cordless drill, and run it spinning into the seating stem to polish the seating stem so that it no longer sticks.

Thankfully i don't have this issue.

DellaDog · Sep 4, 2018

Mordamer said:
A friend and I both had issues with forester's seating stems not fitting correctly on the 140 ELD-M ogive. I had no issues with 2 other bullets I loaded, but the Forester seating stem would stick on the ogive of the 140 ELD and cause inconsistent seating. Often when the press ram was retracted there was a snapping sound of the seating stem popping off the ogive of the bullet. If this sounds like a possible cause in your situation, a fix is to put some polishing compound on the ogive of a bullet, chuck the base end of the bullet in a cordless drill, and run it spinning into the seating stem to polish the seating stem so that it no longer sticks.

I had the exact same issue with Berger 140 Hybrids. Sent the die back to Forster - two weeks later, no more sticking, snapping or popping. (Or rings on the bullet)

Mordamer · Sep 4, 2018

Drewdemon said:
What is an acceptable variance? I measured factory 6.5 CM 140G match ammo and the variance is +/- .003 on all of them. Im not sure i'll get the variance that low but what's within normal limits?

My loads with forester seating die are generally +/- .001. I see no reason why you could not achieve this level of consistency.

Mordamer · Sep 4, 2018

Drewdemon said:
Thankfully i don't have this issue.

You have enough variance in your seating depths that I suspect you do have this issue to some degree even if you don't hear the snapping sound. If the seating stem is also leaving faint scrape marks low on the ogive that is another sign.

mdmp5 · Sep 4, 2018

Drewdemon said:
What is an acceptable variance? I measured factory 6.5 CM 140G match ammo and the variance is +/- .003 on all of them. Im not sure i'll get the variance that low but what's within normal limits?

The "problem" is that the seating stem is not indexing off the engagement diameter of the ogive of the bullet; rather a slightly smaller diameter. If the seating stem was exactly 257, you would have almost identical cbto. That stem is more like 225. The micrometer was meant to be turned, so put it to work

whiskeysierra762 · Sep 5, 2018

I have taken a drill bit to the seating stem of most of my dies that I use to load the newer high BC bullets. I found that the tips were bottoming out in the seating stem and I was seating them off the tip and not the ogive. By drilling out the seating stem a little deeper it fixed the problem.
There is also the possibility if you are running an very compressed load that the powder will push the bullet back out of the case some if you don't have enough neck tension.

spife7980 · Sep 5, 2018

I was having the same issue with my Forster seating die, the popping. Did a little googleing and the search results said to back the die out of the press a turn or two. I did that and I no longer have the popping.

Juggerxxx · Sep 5, 2018

As others have mentioned, Check the tips of the bullets to see if they are deformed giving the indication they are bottoming out and hitting the inside of the stem.
Make sure your neck tension or the inside diameter is the same on all your brass. If the ID differs more than 0.001” this will cause your issue.
Make sure you are measuring correctly. When you have it in the caliper, spin the cartridge to make sure that base is flat and the round is straight.
You should very easily be able to achieve +-0.001”. This is one measurement I am able to consistently achieve in all my calibers and have found that I only need to spot check every 5 or so rounds.

Bradu · Sep 5, 2018

mijp5 said:
The "problem" is that the seating stem is not indexing off the engagement diameter of the ogive of the bullet; rather a slightly smaller diameter. If the seating stem was exactly 257, you would have almost identical cbto. That stem is more like 225. The micrometer was meant to be turned, so put it to work

There is something else going on to have .024" variance. I can see a few thousandths but this is pretty extreme.

I would see where the seating stem is contacting the bullet to see if there is an issue there.

mdmp5 · Sep 5, 2018

If you think you are hitting the tips of the bullet, take the seating stem out and measure the depth of the inside and then see how far the bullet is fitting inside the stem

mdmp5 · Sep 5, 2018

Bradu said:
There is something else going on to have .024" variance. I can see a few thousandths but this is pretty extreme.

I would see where the seating stem is contacting the bullet to see if there is an issue there.

I agree that you have to look at everything. I have seen almost that amount of variance with my 223 using nobler bullets

RTH1800 · Sep 5, 2018

You could soft seat them a little long and let the chamber seat them to place.

mdmp5 · Sep 5, 2018

rth1800 said:
You could soft seat them a little long and let the chamber seat them to place.

That's only if his rifle likes to jam

RTH1800 · Sep 5, 2018

It will prefer jamming to a .024 variation in seating.

mdmp5 · Sep 5, 2018

Hopefully he is on his way to fixing that

spife7980 · Sep 5, 2018

What I notice is that you are getting progressively longer. Unless thats not the order you measured them and you just arranged them like that?

Drewdemon said:
What is an acceptable variance? I measured factory 6.5 CM 140G match ammo and the variance is +/- .003 on all of them. Im not sure i'll get the variance that low but what's within normal limits?

Thats a a fine range, especially for factory ammo. You would be hard pressed to shoot the difference between those depths unless you were right up against the lands.
Plus, the ogive is variable and depending on the tool what your seating die measures vs what your calipers measure could be taken at two different points and so one could be accurate and the other leading you astray but you dont have a way to tell which unless you get more tools to measure those differences. Thats where something like the bob green comparator comes in to play for sorting those differences (the critical distance) if you really want to get into the gritty part of reloading. I dont.

Unless youre going to the effort to sort your bullets based on their ogive profiles I would just leave the seater at one setting and figure out the true cause of your seating issues. .024" of depth differences isnt due to the ogive differences on the bullet, if it is you need to send those bullets back. Check just the bullets with your comparator and see if they have that much variation before seating.

First things first, take the micrometer apart. Grab this knurled section and twist it off of the bottom. You can do this without losing all the setting on your upper half, this just allows you to take the sleeve out and look at the seating stem.

Give it a good cleaning and check the stem for any cracks in it where it touches the bullet. If theres a crack it could spread when you seat the bullet and lead to some issues like yours.
Check the sleeve to make sure it moves freely inside of the die and that a bullet can pass freely through it.

Next take a bullet and put it into the seating stem. Make sure that it shitting on the bullets diameter and not its tip.

If it does bottom out you can send it to forster or get a little lapping compound and make it fit by chucking a sacrificial bullet or two into a drill and running it into the seating stem to make it fit.

After you do that and it all checks out give it an oiling and put it back together. Then back it out of the press a turn or two and readjust your micrometer to get your seating depth back. See if that fixes it.
It could be that your new brass is so crazy varied inits amount of neck tension it left the factory with that it resists sizing that much but I highly doubt it could lead to that much variation.

Vig_1016 · Sep 5, 2018

I've had consistent bto measurements using the redding competition die and the vld seating stem.

Drewdemon · Sep 5, 2018

I appreciate all of the feedback. I'm going to start out with pulling the die apart, cleaning , then checking if the bullet tip is touching. I have an extra forester micrometer die, i can see what kind of results i get i with that.

spife7980, on a side note, thanks for the magazine help. The new mags you suggested work 100% better than the stock ones.

ShtrRdy · Sep 5, 2018

Are you dealing with a compressed powder charge?

Wheedle · Sep 5, 2018

Drewdemon said:
What is an acceptable variance? I measured factory 6.5 CM 140G match ammo and the variance is +/- .003 on all of them. Im not sure i'll get the variance that low but what's within normal limits?

I'm just going fto give my honest opinion here as a machinist of 20-odd years...
If you are using any sort of calipers to measure, .003 is within the variance of the tool as used. Professionally, anything I have to know to less than +/- .003, I use a micrometer, or figure out a gauging setup using some sort of standard or gauge blocks and a dial indicator. Calipers inherently have some flex and give to the jaws, and then there is finger pressure and feel.

But I am a crusty, grumpy, old fuck wiith a touch of OCD...

mdmp5 · Sep 6, 2018

spife7980 said:
What I notice is that you are getting progressively longer. Unless thats not the order you measured them and you just arranged them like that?

Pretty sure he just organized them like that to make it easier to read

Drewdemon · Sep 6, 2018

Wheedle said:
I'm just going fto give my honest opinion here as a machinist of 20-odd years...
If you are using any sort of calipers to measure, .003 is within the variance of the tool as used. Professionally, anything I have to know to less than +/- .003, I use a micrometer, or figure out a gauging setup using some sort of standard or gauge blocks and a dial indicator. Calipers inherently have some flex and give to the jaws, and then there is finger pressure and feel.

But I am a crusty, grumpy, old fuck wiith a touch of OCD...

Im using the Mitutoyo (CD6-ASX) calipers with hornady to measure ogive.

Drewdemon · Sep 6, 2018

mijp5 said:
Pretty sure he just organized them like that to make it easier to read

They are not in any particular order. I ordered them for my charts just to get an understanding of the variance

Drewdemon · Sep 6, 2018

ShtrRdy said:
Are you dealing with a compressed powder charge?

I don't think so, the charge i'm using is 42.6g

1J04 · Sep 6, 2018

spife7980 said:
What I notice is that you are getting progressively longer. Unless thats not the order you measured them and you just arranged them like that?

Thats a a fine range, especially for factory ammo. You would be hard pressed to shoot the difference between those depths unless you were right up against the lands.
Plus, the ogive is variable and depending on the tool what your seating die measures vs what your calipers measure could be taken at two different points and so one could be accurate and the other leading you astray but you dont have a way to tell which unless you get more tools to measure those differences. Thats where something like the bob green comparator comes in to play for sorting those differences (the critical distance) if you really want to get into the gritty part of reloading. I dont.

Unless youre going to the effort to sort your bullets based on their ogive profiles I would just leave the seater at one setting and figure out the true cause of your seating issues. .024" of depth differences isnt due to the ogive differences on the bullet, if it is you need to send those bullets back. Check just the bullets with your comparator and see if they have that much variation before seating.

First things first, take the micrometer apart. Grab this knurled section and twist it off of the bottom. You can do this without losing all the setting on your upper half, this just allows you to take the sleeve out and look at the seating stem.

View attachment 6940548

Give it a good cleaning and check the stem for any cracks in it where it touches the bullet. If theres a crack it could spread when you seat the bullet and lead to some issues like yours.
Check the sleeve to make sure it moves freely inside of the die and that a bullet can pass freely through it.

Next take a bullet and put it into the seating stem. Make sure that it shitting on the bullets diameter and not its tip.
View attachment 6940551

If it does bottom out you can send it to forster or get a little lapping compound and make it fit by chucking a sacrificial bullet or two into a drill and running it into the seating stem to make it fit.

After you do that and it all checks out give it an oiling and put it back together. Then back it out of the press a turn or two and readjust your micrometer to get your seating depth back. See if that fixes it.
It could be that your new brass is so crazy varied inits amount of neck tension it left the factory with that it resists sizing that much but I highly doubt it could lead to that much variation.

THIS

AND THIS

CAN HAVE THE SAME EXACT ISSUES IF YOU DON'T KNOW THAT IT'S HAPPENING OTHER THAN MY CBTO NUMBERS KEEP CHANGING. MY ISSUE WAS BOTTOMING OUT IN THE COMPARATOR ON LONGER VLD'S. SO I GOT ONE OF THESE AND THE PROBLEM WENT AWAY.

NOT THE ACTUAL COMPARATOR, BUT CLOSE ENOUGH TO THE ONE I GOT.

Drewdemon · Sep 6, 2018

I think you guys nailed it. I took it apart, cleaned it, put it back together and now it's making the popping sound. Like it's stuck

Mordamer · Sep 6, 2018

Drewdemon said:
I think you guys nailed it. I took it apart, cleaned it, put it back together and now it's making the popping sound. Like it's stuck

Called it.

spife7980 · Sep 6, 2018

Hav you backed it out of the press a turn or two yet?

Drewdemon · Sep 7, 2018

spife7980 said:
Hav you backed it out of the press a turn or two yet?

Going to try that today. Also sent an email to Forster and will probably give the polishing compound a try.

Wheedle · Sep 7, 2018

Drewdemon said:
Im using the Mitutoyo (CD6-ASX) calipers with hornady to measure ogive.

Fine set of digitals. I have that same set, think I bought them in 99 or so, so I could bring my dad's Starrett dials home. Using a setup like that where the gauge clamps to one jaw will help eliminate a lot of the variables. A consistent, very light touch on the thumbwheel and ensuring that the base of the cartridge is in full contact with the other jaw is vital. I still believe a setup akin to this would be better, but I haven't really seen anything set up for OAL measurement.

I need to get setup to reload, .300 WM is getting spendy. I do have the advantage of already owning several dial indicators and bases ad being able to make pretty much whatever I need.

Drewdemon · Sep 8, 2018

spife7980 said:
Hav you backed it out of the press a turn or two yet?

I tried backing it out one, then two, and even three but i still had the "pop". The sound was less severe but after backing it out allot i was running out of adjustment room. I'll try the polishing compound next. If that doesn't do it I'll wait for Forester to send the replacement seating system.

"I want to try sending you a replacement seating stem. It sounds as if potentially that one has flared out. We see this most often if it encounters some extra pressures. If you have the same issue with this replacement, we will likely need the die sent in with some sample cases you have prepped and bullets for review. Please provide me your address."

spife7980 · Sep 17, 2018

Drewdemon said:
I tried backing it out one, then two, and even three but i still had the "pop". The sound was less severe but after backing it out allot i was running out of adjustment room. I'll try the polishing compound next. If that doesn't do it I'll wait for Forester to send the replacement seating system.

"I want to try sending you a replacement seating stem. It sounds as if potentially that one has flared out. We see this most often if it encounters some extra pressures. If you have the same issue with this replacement, we will likely need the die sent in with some sample cases you have prepped and bullets for review. Please provide me your address."

Going to have to eat a bit of crow.
I was given fits with it again yesterday all of the sudden when after seating the first 20 cases when it showed back up with a vengeance. And while backing it out a bunch did help it would last for around 40 rounds before the pop would suddenly come back again. Did it several different times in my session.
Before I had backed it out and it was fine for a couple hundred after. Yesterday it would only last for around 40 rounds before coming back all of the sudden.

Ive send out a request for helpon the contact is bit of their web page. Hope they will just mail me a stem right away

Drewdemon · Sep 18, 2018

spife7980 said:
Going to have to eat a bit of crow.
I was given fits with it again yesterday all of the sudden when after seating the first 20 cases when it showed back up with a vengeance. And while backing it out a bunch did help it would last for around 40 rounds before the pop would suddenly come back again. Did it several different times in my session.
Before I had backed it out and it was fine for a couple hundred after. Yesterday it would only last for around 40 rounds before coming back all of the sudden.

Ive send out a request for helpon the contact is bit of their web page. Hope they will just mail me a stem right away

I measured the seating stems and support said it "might be the issue" .

Original seating system .264
Replacement seating system .261

I reloaded about 50 rounds and a few of them popped. I told support and sent them of video of the "pop". We'll see what happens next. I have a feeling you have to be gentile when seating. No extra force with the downward motion.

Drewdemon · Sep 24, 2018

I seated about 100rounds over the weekend. None of them had the "pop" sound. I did find myself adjusting the micrometer each time to get a +/- .003 variance. Since i'm new to reloading i expected once the micrometer was set you blew threw rounds without checking. I've since readjusted my expectations. I may buy some high end brass and see what happens.

spife7980 · Sep 24, 2018

I never got that much variance, maybe an entire range of .003 with just being under .001 difference. So I have always been able to just set it and go.

I got my new stem in as well only now I have the dumb problem of being out of 6mm bullets to use it with. It is .002 narrower though, so maybe it spreading and growing wider is the issue.

Muley Buck · Dec 1, 2019

Resurrecting this thread. Did everyone or anyone get a proper solution to the "popping" seating stem issue?

mustang-cars · Dec 1, 2019

Muley Buck said:
Resurrecting this thread. Did everyone or anyone get a proper solution to the "popping" seating stem issue?

I finally had to go away from my Forster seater. They stopped hardening their seating stems awhile back. The mouth of the stem is very thin which provides for a very close tolerance between the stem and sleeve (low run out), but allows the mouth of the seating stem to flare with use causing inconsistent seating depths. I switched to the Redding micrometer seater with VLD stem and have about 4,000 rounds on that seater and it has always seated to within .002 CBOG extreme spread. It’s usually better but that’s the worst it ever is. Just my .02

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