Neck Sizing Question

[Racinready300ex]

I'm getting some vertical fliers in my groups, and think it has to do with my neck sizing. (5 shot groups with 3-4 shot's in 1.5-2" and the other 1 or 2 shots 6" high at 600 yards)

I feel like it's probably something wrong with my load. The one area I don't feel right about is the neck sizing.

I use a lee neck die, per instructions. Run die down till it touches shell holder plus one more turn. When I do this I can't do a full stroke on the press with a case in there. It seems to me that my neck tension would depend on the pressure I apply to the case, and not be very consistant.

My thought is to back out the die until I can get a full stroke on the press and close the neck enough to hold the bullet. (this takes backing out the die about .25 a turn) Then I will go all the way to the stop and it should be the same every time.

So does that make sense? Could that be my problem and a possible solution?

Oh and this is a bolt action.

 

[Captain Kirk]

Re: Neck Sizing Question

6" high fliers, thats very odd, you may have some optics/base issues or rifle/bedding issues. Picking up a box of factory match ammo will be a good idea, alleviate any possibility of it being your load.


The easiest way to determine your actual neck tension is as follows;

1. Measure the case neck diameter of a loaded round
2. Measure the case neck diameter of a freshly resized case (no bullet)

This will give you a #, say a loaded round is .339 and a resized case is .337, your actual neck tension of a loaded round is .002, a good # is .0015-.003, any more than .003 and you are risking overworking your case necks which can dramatically shorten their life.

Kirk R

 

[MitchAlsup]

Re: Neck Sizing Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Racinready</div><div class="ubbcode-body">I'm getting some vertical fliers in my groups, and think it has to do with my neck sizing. </div></div>

What physical effect can you imagine that would cause a round case holding a round bullet in a round chamber to only have only vertical fliers?

 

[Racinready300ex]

Re: Neck Sizing Question

I was thinking it would effect the pressure and the velocity.

 

[Racinready300ex]

Re: Neck Sizing Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Captain Kirk</div><div class="ubbcode-body">6" high fliers, thats very odd, you may have some optics/base issues or rifle/bedding issues. Picking up a box of factory match ammo will be a good idea, alleviate any possibility of it being your load.


The easiest way to determine your actual neck tension is as follows;

1. Measure the case neck diameter of a loaded round
2. Measure the case neck diameter of a freshly resized case (no bullet)

This will give you a #, say a loaded round is .339 and a resized case is .337, your actual neck tension of a loaded round is .002, a good # is .0015-.003, any more than .003 and you are risking overworking your case necks which can dramatically shorten their life.

Kirk R </div></div>

I have about 20 rounds loaded at home, and about that many sized too. I play around with measureing that tonight if I have the time.

 

[TimK]

Re: Neck Sizing Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Racinready</div><div class="ubbcode-body">I was thinking it would effect the pressure and the velocity. </div></div>

I'll bet you can go from a min to a max load and not get a change in POI of 6". (Assuming you're talking about groups at 100 yards) Neck tension is not your problem.

 

[Racinready300ex]

Re: Neck Sizing Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tim K</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Racinready</div><div class="ubbcode-body">I was thinking it would effect the pressure and the velocity. </div></div>

I'll bet you can go from a min to a max load and not get a change in POI of 6". (Assuming you're talking about groups at 100 yards) Neck tension is not your problem. </div></div>

Groups were at 600 yards,

I thought I put that in there. But didn't. Last time I was shooting at 100 I was seeing some groups all touching, but here and there I would get one that was off vertically .5" or so.

 

[Chanonry]

Re: Neck Sizing Question

A lee collet die? I have a set and I understand what you mean about variable tension but it does not produce an effect of the magnitude you are seeing down range.

Within reason, it is an optimisation variable to control not one of the fundamentals.

 

[Fred_C_Dobbs]

Re: Neck Sizing Question

I have Lee collet dies in three calibers and I've found you have fiddle with each a bit to find the "sweet spot" as far as leverage goes. It can be as little as a quarter of a turn of the die body. Once you hit it, 20-25# of pressure is all you need. 500# of pressure will not produce and difference from 25#. As I'm adjusting the die, I size a case, then test by inserting the bullet's boattail into the mouth of the case. If the boattail goes in as far as the shoulder at the shank, it is not properly sized.

Your OE mandrel should be 0.002" smaller than your caliber. Lee will sell you any size you want in 0.001" increments so you can tweak neck tension to suit.

This weekend I shot a couple of 10-shot groups @400 yards, all 20 were neck sized with a Lee collet die. One target had eight rounds in a tidy little group and two were ~3" high. On the other target, nine rounds were bunched up and one was ~3" higher. The three "flyers" also all had a MV about 15 fps faster than the fastest of the other 17 rounds. In my case, I blame the the inconsistent MV.

 

[jagged77]

Re: Neck Sizing Question

Not sure about the solution to your problem but I can advocate the other method of using the collet dies. I set mine so the press fully closes (have used a rock chucker and Co-Ax) and the die is adjusted so that the neck gets just the right amount of tension every time when the press is at the top of the stroke.

 

[Nessal]

Re: Neck Sizing Question

I use the neck sizer until the bolt gets hard to lift. That way I work the brass less. I used to full size my brass and I can tell at about 5-7 loadings, the head is starting to get thin.

Btw, I believe it doesn't matter how much pressure you put into the Lee neck sizing die. It will still size to the same amount of tension as long as you get the collet to close onto the mandrel. Take apart the die and you will see what I mean. As long as the case is loaded into the die and the ram is closed enough that the collet fingers presses against the neck into the mandrel, extra pressure from then on does essentially nothing.

 

[Fuzzball]

Re: Neck Sizing Question

"It seems to me that my neck tension would depend on the pressure I apply to the case, and not be very consistant."

Not really, at least not if you are putting enough pressure on the die to insure the neck is actually hard against the mandral. Additional pressure after that means nothing to the necks.

Pressure changes do affect speeds but the point of impact can go in any direction because of viberations. Thinking of shifts only in terms of speed is much too simplistic.

 

[jagged77]

Re: Neck Sizing Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Nessal</div><div class="ubbcode-body">

As long as the case is loaded into the die and the ram is closed enough that the collet fingers presses against the neck into the mandrel, extra pressure from then on does essentially nothing. </div></div>

Excess pressure can cause the shoulder to bulge or buckle.

One of the main benefits of the Lee collet is the minimal working of the brass. The aim should be to size the neck and set the tension so that a functional and safe case can be achieved with the least amount of working.
By setting the press to fully close and adjusting the collet die height you can achieve that exact end repeatedly. I used to do it the way prescribed in the instructions but found this way much easier. Each to their own though.

 

[MitchAlsup]

Re: Neck Sizing Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body">Your OE mandrel should be 0.002" smaller than your caliber. Lee will sell you any size you want in 0.001" increments so you can tweak neck tension to suit.</div></div>

I agree with Fred, it is time to start measuring the output of the neck sizing operation to see if everything comming out has the same dimensions, and concentricity.

 

[Racinready300ex]

Re: Neck Sizing Question

I measured about 20 sized cases and found them to be .247 to .248. My loaded rounds were all .249 except for 2 at .250

Granted it would be nice to have measured the rounds the where off. And I may need to upgrade from my cheap harbor freight calipers. I doubt there accurate at .001

From the sounds of it this probably isn't my problem. But, I'll find it.

Thanks for the input

 

[MitchAlsup]

Re: Neck Sizing Question

I think its time to look elsewhere for your vertical problem.