Strange Seating Variable

[Lapua40X]

I am seating 180 grain Berger .284 HP VLD Target Bullets with a Redding Micrometer seating die. After adjusting the die and verifying the seating depth on two successive rounds I usually continue; typically checking every fifth round for consistency. But this time I ran a couple of dozen - ignorant confidence in the quality of the products.
These Berger bullets varied in seating depth by as much as .005. The differences in seating depth were not linear over the total sample. Some were out .001, others more. One could be right on, the next .003 over, the next .002 under, etc.
The die has two seating stems, one that is machined with a longer taper for VLD bullets. That's the stem I used initially and, to determine whether or not the stem was an issue, I tried the other stem to see if there was any difference in the variable - results were the same.
The die and the components of the press (shell holder, etc.) are surgically clean.
The only variable I can think of is the of the consistency of the bullet's physical profile.
Any other ideas ???????????????

 

[BoydAllen]

The first thing that I would do is to check the bullets. This is not precise, but I would use an ogive checker attachment and measure them from base to ogive, to see how uniform they are. If I wanted to take it farther, I would use the smallest caliber ogive insert to make a second measurement of each bullet. If I were going to this trouble, I would put 20 bullets into a tray for holding cases, and assign each position a number on a table, then I would measure each bullet using the insert for their caliber, and then again with an insert that contacted them in about the same place as the seating stem. At that point I would subtract the smaller of the two from the larger, and note the bullet to bullet variance of this difference. One of the determining factors of seating depth consistency is how uniform the curve of the ogive is. If the distance between where the seater stem makes contact, and where the rifling will make contact varies, so will the seating depth.

 

[Keith Glasscock]

My press is a little worn. It will vary the seating depth with seating force, powder compression, and operator technique.

If you are running barely compressed or just barely not compressed loads with extruded powders, that can be your problem.

 

[Raythemanroe]

New brass? Tight primer pockets could be preventing them from getting seated all the way..


Ray

 

[mudduck]

I have been having the same problem with Forster mic die to. Put my lee seater in and the all come out the same depth. Hope someone knows what's going on

 

[Patch700]

I have been having the same problem with Forster mic die to. Put my lee seater in and the all come out the same depth. Hope someone knows what's going on

The bigger question may be what bullet are you having these problems with as opposed to the die... I had a scenario not unlike yours and after repeatedly dis-assembling the die looking for a problem (the stem did require polishing) I found that the problem was actually as boyd mentioned , a descrepency in the the dimension of the bullet where the stem makes contact.. Seeing as the stem does'nt actually touch where the actual ogive is. The bullet in question was a 140 A-Max , and although the barrel shot them very well i had to do a fair bit of sorting to get to that point.

 

[lpreddick]

base to ogive can vary as much a .020+ so i sort bullets ...once had a box that only had 8-10 measuring the same! the most common cause for me getting variation in base to ogive seating is variation in neck tension such that the bullet enters the hollow seating stem... if the tip doesn't bottom out in the stem. i can see the imprint of the stem on the bullet being longer if the measurement is too long. on the other hand, if neck tension is less, the bullet will seat very easily and measured depth will be too short. once again neck tension variations is bitting my butt.

 

[Alex Wheeler]

The first thing that I would do is to check the bullets. This is not precise, but I would use an ogive checker attachment and measure them from base to ogive, to see how uniform they are. If I wanted to take it farther, I would use the smallest caliber ogive insert to make a second measurement of each bullet. If I were going to this trouble, I would put 20 bullets into a tray for holding cases, and assign each position a number on a table, then I would measure each bullet using the insert for their caliber, and then again with an insert that contacted them in about the same place as the seating stem. At that point I would subtract the smaller of the two from the larger, and note the bullet to bullet variance of this difference. One of the determining factors of seating depth consistency is how uniform the curve of the ogive is. If the distance between where the seater stem makes contact, and where the rifling will make contact varies, so will the seating depth.

+1
If your not sorting you bullets you won't get consistent seating depth.

 

[dkhunt14]

If the brass is new or cleaned really good it takes a lot of pressure to seat bullets. Sometimes with the tension I run I have to really lean on the arbor press or put the longer one back in and really push down on the handle to get them to seat to even thousandths. If the seater stem is hitting the point and not on the ogive it could probably vary the seating depth. Matt

 

[jr600yd]

I've had many of the same problems mentioned. Solved most of them as describe above. However, I had a set of Redding dies in 308 that were driving me nuts. What it finally came down to was thread slop. (thread slop between die and press, seating stem and die) Once removed everything came out perfect. Just something to keep in mind.

 

[243winxb]

The Redding Competition Seater Die may be lightly adjusted to contact the shell holder . This acts as a stop for the press linkage removing any slop from wear. Dont over look the Lee Dead Length bullet seating die. It works on the same principle. But check the bullets first.

 

[ftrrookie]

Boyd and zfast are correct that sorting is the best route to get consistent seating depth. And it's what I used to do until I saw a video of another technique. It works best if you have a turret press or 2 single stage presses and you will need a Redding instant indicator in your calibers.
Here's what I do. Using a comparator I seat my first bullet to the depth I want. Put that round in the ii and adjust the dial indicator to zero. Back off my seating depth by a few thou and seat a bullet. Move over to the ii and see how far I'm out. Adjust the die that amount and seat the bullet to it's final depth. Do this for every round. All bullets are seated to the same BTO length.

Just one word of warning. If doing this on a turret press make sure the bullet has cleared the die before you start to turn the turret. Failure to do so plays hell with concentricity. :

 

[jlow]

Boyd and zfast are correct that sorting is the best route to get consistent seating depth. And it's what I used to do until I saw a video of another technique. It works best if you have a turret press or 2 single stage presses and you will need a Redding instant indicator in your calibers.
Here's what I do. Using a comparator I seat my first bullet to the depth I want. Put that round in the ii and adjust the dial indicator to zero. Back off my seating depth by a few thou and seat a bullet. Move over to the ii and see how far I'm out. Adjust the die that amount and seat the bullet to it's final depth. Do this for every round. All bullets are seated to the same BTO length.

Just one word of warning. If doing this on a turret press make sure the bullet has cleared the die before you start to turn the turret. Failure to do so plays hell with concentricity. :

One thing to keep in mind with this method is although you are getting consistent base to ogive lengths for the loaded round, the actual seating depth of your bullet may still vary due to differences in base to ogive length of your bullet which in turn may have slight effects on your chamber pressure and precision. For this reason, you are still better off sorting bullets by base to ogive length first to get consistent loaded round lengths.

 

[Footsore]

I have been having the same problem with Forster mic die to. Put my lee seater in and the all come out the same depth. Hope someone knows what's going on

The bigger question may be what bullet are you having these problems with as opposed to the die... I had a scenario not unlike yours and after repeatedly dis-assembling the die looking for a problem (the stem did require polishing) I found that the problem was actually as boyd mentioned , a descrepency in the the dimension of the bullet where the stem makes contact.. Seeing as the stem does'nt actually touch where the actual ogive is. The bullet in question was a 140 A-Max , and although the barrel shot them very well i had to do a fair bit of sorting to get to that point.

I have a new Forster seater that does the same with sorted bullets in 6.5 cal. But! the comparator i use measures at a different point on the bullet nose to where the seater contacts. The seater is a slightly larger diameter and contacts further back. Unless you are measuring at the same place any irregularity in shape at the nose can give a variation even if the die is seating perfectly. So it may not be the ammo is not right just the measuring technique.

 

[jlow]

I have been having the same problem with Forster mic die to. Put my lee seater in and the all come out the same depth. Hope someone knows what's going on

The bigger question may be what bullet are you having these problems with as opposed to the die... I had a scenario not unlike yours and after repeatedly dis-assembling the die looking for a problem (the stem did require polishing) I found that the problem was actually as boyd mentioned , a descrepency in the the dimension of the bullet where the stem makes contact.. Seeing as the stem does'nt actually touch where the actual ogive is. The bullet in question was a 140 A-Max , and although the barrel shot them very well i had to do a fair bit of sorting to get to that point.

I have a new Forster seater that does the same with sorted bullets in 6.5 cal. But! the comparator i use measures at a different point on the bullet nose to where the seater contacts. The seater is a slightly larger diameter and contacts further back. Unless you are measuring at the same place any irregularity in shape at the nose can give a variation even if the die is seating perfectly. So it may not be the ammo is not right just the measuring technique.

It is true that the bullet can vary both in terms of length and/or shape but the reality is by at least eliminating one, you stand a better chance to get consistent base to ogive length for a loaded round. I sort all my bullets this way and I am happy to report that the base to ogive lengths for my loaded rounds usually do not vary much and when they do, it is only around 1 thousands.

 

[Lapua40X]

UPDATE ....

i checked the length of a box of my Berger 180 grain Target .284 bullets. Lengths varied as much as .004
I checked the Hornady Lock-N-Load Bullet Comparator Anvil Base - found a slight crown (.0015+/-) so it isn't as flat as it should be.
Checked the seating stem with some Prussian Blue and found, even though it is designed for the bullet I'm loading, the stem's contact area on the bullet nose is really quite narrow.
I'm going to try adjusting the amount of contact between the case holder and the sleeve of the die (as was suggested by one of our members), measure the finished lengths using the caliper without the anvil base, and see how much that improves results.
Thanks for all the input. It is GREATLY appreciated.