Inconsistent seating depth

[girish]

I'm having a problem with seating depth in 223. I have been using 77 Sierra Matchkings without issue. I decided to try Berger 85.5 Hybrids, but about 15 to 20 percent of the loaded rounds are seated .030 to .035 deeper (actually 30 thousandths or more too deep) as measured cartridge base to ogive with a Hornady comparator.

I'm using Lapua brass, RCBS Rebel press, and Lee bullet seating die that came with the collet neck sizing die. I routinely seat bullets a second time after turning the case in the shell holder. I have checked carefully and the Bergers do not come anywhere close to bottoming out in the seating stem/plug. The die is clean and the shell holder is clean. Overall length of the Berger bullets themselves base to tip have up to .015 spread but most are less than that. Bullet base to ogive with the Hornady comparator has about .004 spread. I also checked bullet length using the seating plug as a comparator, which contacts the bullet in between the tip and where the Hornady comparator does. That varied about .003.

What can cause some of these Bergers to seat so much deeper?

 

[762plinker]

check and see if the bullet tips are hitting the top of the seater stem...may need a diff seater or sometimes one can carefully drill the seater stem for tip clearence

 

[BoydAllen]

I believe that that is a dead length seater. Do you have it set to toggle a little on the shell holder?

 

[girish]

check and see if the bullet tips are hitting the top of the seater stem...may need a diff seater or sometimes one can carefully drill the seater stem for tip clearence

Thanks for the suggestion but I tried to explain above that the tip of the Berger does not touch in the stem. Not even close.

 

[girish]

I believe that that is a dead length seater. Do you have it set to toggle a little on the shell holder?

Yes, it is the dead length seating die. I followed the Lee instructions that said to screw the die in until it touches the shell holder plus another 1/4 turn.

 

[Ned Ludd]

I would suggest length-sorting some bullets (OAL). Then seat a few that all sort to within ~.002" of each other (i.e. a single length-sorting group). That should at least remove most of the potential seating depth variance due to bullet length variance. If you still have issues with seating depth variance (i.e. CBTO variance), you should have a better idea of the actual magnitude, which might suggest what the issue is, or may provide some indicator as to what to look for. If you decide to do this, let us know how the seating depth consistency compares with that derived using un-sorted bullets (i.e. 0.030" to 0.035" seating depth variance as mentioned above).


Here are a few other ideas:

Are these compressed loads? In other words, can you feel powder crunching when you seat the bullets? This can definitely result in inconsistent seating depth.

What amount of neck tension (interference fit) are you using? Excessive neck tension can sometimes result in inconsistent seating depth.

Are the case mouths well-chamfered? This can affect seating depth consistency.

Do the case necks have donuts? This can usually be felt as a noticeable compression ring near the bottom of the neck when seating the bullet bearing surface below the neck shoulder. Unless one is using a chamber with very generous freebore, even 77 SMKs will be seated well below the neck/shoulder junction in a .223 Rem case, such as in mag-length loads. This can sometimes affect seating depth consistency.

 

[Dimner]

When I first started reloading for under moa, I had the same problem. Need hit the specifics that fixed this issue for me.

-Sort bullets by base to ogive
-Anneal brass fully for consistent neck tension
-avoid compressed load

Of these three things, consistent annealing is very important. Inconsistent annealing will still make your brass life last for ever, but not help with neck tension.

Well, there was one more thing I did at the same time. I used only brass of the same lot. Of course I shot each case multiple times, but when I stopped using range pickup brass or someone else's once fired brass, my neck tension consistency increased greatly. Buy a new bag of 50 cases and try it out.

 

[Coyotefurharvester]

Are you seating shorter than overall length minimum for the Berger bullet? 2.373"(1.750 case length) Tip of bullet to start of bearing surface is 0.623.

 

[urbanrifleman]

Donut.

 

[JFrank]

I'm having a problem with seating depth in 223. I have been using 77 Sierra Matchkings without issue. I decided to try Berger 85.5 Hybrids, but about 15 to 20 percent of the loaded rounds are seated .030 to .035 deeper (actually 30 thousandths or more too deep) as measured cartridge base to ogive with a Hornady comparator.

I'm using Lapua brass, RCBS Rebel press, and Lee bullet seating die that came with the collet neck sizing die. I routinely seat bullets a second time after turning the case in the shell holder. I have checked carefully and the Bergers do not come anywhere close to bottoming out in the seating stem/plug. The die is clean and the shell holder is clean. Overall length of the Berger bullets themselves base to tip have up to .015 spread but most are less than that. Bullet base to ogive with the Hornady comparator has about .004 spread. I also checked bullet length using the seating plug as a comparator, which contacts the bullet in between the tip and where the Hornady comparator does. That varied about .003.

What can cause some of these Bergers to seat so much deeper?

15-20% vary .030 -.035 in seating depth results when compared with a Hornday tool ?

This doesn’t sound like a bullet sorting issue.

 

[girish]

It's a bit overwhelming the generosity of people here sharing their expertise. It is greatly appreciated. I'll try to address the suggestions here.

Loads are not compressed.
Neck tension is about 1 1/2 to 2 thousandths, as measured by the outside neck diameter before and after seating.
Case mouths are chamfered.
All brass is from the same Lapua box.
I did not get as much freebore with the barrel as I expected, so both the 77 Sierras and 85.5 Bergers are seated way below the case neck/shoulder junction. I'm using lower powder charges because of that.
After firing 60 rounds I get a few, usually less than six, donuts. I check for donuts before loading and remove them. The cases that had donuts do not correlate with the rounds that get seated too deep.
Cases are trimmed to 1.750.
The 80% that are consistently seated with Bergers are about COAL 2.430, with some variation from the bullet OAL. The 20% that are seated way too deep are obviously much shorter than that.
I don't anneal. Induction annealing seems the way to go but it is not in the budget right now.

I'll keep bullet sorting as an option if I don't figure out the problem before that. 80 percent or more of the rounds seat rather consistently, and then those 15-20 percent are way deeper than the rest. The deep rounds are seated deeper by 2 or 3 times the OAL variation of the bullets, and around 10 times more than the bullet BTO variation.

The problem does not happen with the 77 gr Sierras which have a less pointy profile. The Bergers are much more pointy but they still only extend into the seating stem about halfway to the end of the cavity, so the tip of the Bergers do not come anywhere close to touching the stem.

I wondered if perhaps the seating stem/plug was becoming cocked inside the die cap, but after checking I can't even purposely make that happen.

I contacted Lee. They said since the Bergers have more taper that they recommended buying a custom seating plug. I don't understand how the seating plug cavity profile can cause such dramatic depth differences when the bullet tip doesn't touch, but I'm considering buying one.

 

[Bill Norris]

Is the base of the bullet touching the powder ?
Are you raising the ram and stopping with the same amount of pressure on the handle ?
Is the press handle bouncing at the end of the stroke ?

 

[Silo1616]

Mark the bullet and case on a long and short example. Pull both bullets and powder. Resize brass. Swap bullets between cases and reseat and measure. If the short condition moves to the other case - bullet issue. If it stays with the case - brass problem. Not a cure, but may help narrow the fault.

 

[girish]

Is the base of the bullet touching the powder ?
Are you raising the ram and stopping with the same amount of pressure on the handle ?
Is the press handle bouncing at the end of the stroke ?

The base of the bullet may be close to the powder but does not crunch it.
Press handle does not bounce. Trying to use consistent force on the press handle, but it doesn't take much.

 

[CharlieNC]

Any problem with the 77smk?

 

[MagnumW]

A very good annealer can be had for $20 at your local Harbor freight. Just spin brass in a socket in a cordless drill over a propane torch. I have an AMP. The torch does just as well on target. Turn off lights, spin til shoulder of brass starts to turn dull red. Count how many seconds (4 to 6) Try a couple tomes, turn on lights and do the rest.

 

[Coyotefurharvester]

The Lee tech is correct, the hybrid shape of the Berger doesn't play well with the seater. You did adjust the seater stem for when changing bullets(I hope).

 

[longbow]

I'll tell ya.Dont turn your brass to a dull red,you'll ruin it. Turn off the lights so ambient light in the room. You want just a light brown on your brass...that will do it. you want consistent brass. Have been annealing over 20 years with the Ken light annealer. All I need. Read this and learn. If you want to.

Ken Light Manufacturing: How to Anneal

 

[Ned Ludd]

It's a bit overwhelming the generosity of people here sharing their expertise. It is greatly appreciated. I'll try to address the suggestions here.

Loads are not compressed.
Neck tension is about 1 1/2 to 2 thousandths, as measured by the outside neck diameter before and after seating.
Case mouths are chamfered.
All brass is from the same Lapua box.
I did not get as much freebore with the barrel as I expected, so both the 77 Sierras and 85.5 Bergers are seated way below the case neck/shoulder junction. I'm using lower powder charges because of that.
After firing 60 rounds I get a few, usually less than six, donuts. I check for donuts before loading and remove them. The cases that had donuts do not correlate with the rounds that get seated too deep.
Cases are trimmed to 1.750.
The 80% that are consistently seated with Bergers are about COAL 2.430, with some variation from the bullet OAL. The 20% that are seated way too deep are obviously much shorter than that.
I don't anneal. Induction annealing seems the way to go but it is not in the budget right now.

I'll keep bullet sorting as an option if I don't figure out the problem before that. 80 percent or more of the rounds seat rather consistently, and then those 15-20 percent are way deeper than the rest. The deep rounds are seated deeper by 2 or 3 times the OAL variation of the bullets, and around 10 times more than the bullet BTO variation.

The problem does not happen with the 77 gr Sierras which have a less pointy profile. The Bergers are much more pointy but they still only extend into the seating stem about halfway to the end of the cavity, so the tip of the Bergers do not come anywhere close to touching the stem.

I wondered if perhaps the seating stem/plug was becoming cocked inside the die cap, but after checking I can't even purposely make that happen.

I contacted Lee. They said since the Bergers have more taper that they recommended buying a custom seating plug. I don't understand how the seating plug cavity profile can cause such dramatic depth differences when the bullet tip doesn't touch, but I'm considering buying one.

Some time ago, I started buying a VLD seater stem with every Type S Redding setup I have (same idea as the Lee "custom plug" setup you mentioned). The VLD stems work just fine with bullets that have a relatively short and blunt nose, but they also work with the very long and pointy VLD-type bullets I find myself using more often these days. So I simply replace the standard stem straight out of the gate. Only in one case do I know with certainty that the bullets I was using were actually "bottoming out" in the standard stem, but with the VLD stems, it's simply no longer a concern, even if it wasn't a necessity. They're not stupidly expensive, so it may be worth it to you to swap out the stem, although that isn't necessarily guaranteed to fix this seating issue you're having.

Depending on how many times you've fired the brass, not annealing it could be part of the issue. It is usually possible to feel the difference in seating force necessary with brass that has not been annealed after as few as 3-4 firings. Regardless of what some may think, annealing with a torch setup to dull cherry red in a darkened room does not "ruin" the brass in any way, shape, or form. That is complete disinformation. If you decide to begin annealing your brass, there are torch-based setups available for much less than an induction annealer. In fact, some use the old standby of a simple torch and a socket wrench to hold the piece of brass while it is annealing. I believe the available machines will make the process much easier and more consistent than doing it by hand with a socket wrench, but if you just want to try annealing a few pieces, the socket setup should work well enough with costing a lot of money. Just be warned that there are almost as many opinions about how to properly anneal brass as there are people doing it, so be prepared to filter through the information that is out there if you decide to start annealing your brass.

 

[gme]

so I have had this issue with a Lee dead length seater once, the threads for the knurled knob (that controls seating depth) were cut way oversize, when the floating seater plug would contact the knob it would rise (because the slop in the threads) and dependent on the amount of neck tension variation would give in inconsistent seating depth