Neck Sizing Problems

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D.B. Cooper

D.B. Cooper

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So. I'm having problems with neck sizing/neck tension. I just ran 50 cases through my Lee sizing die. Trimmed to length. Deburred. Out of the 50, 12 are so big that there is no resistance on the press lever when seating. The projectiles almost fall right through. (On 2-3 cases, the projectiles will fall right through.) I dumped the powder out of three of them, decapped, and resized. Of the three, one would take a projectile properly.

I took some measurements and found that the cases that won't take a projectile are .240+" and the ones that worked have an ID of 2.35 or less.

I processed them all the same way at the same time. Some RP brass, some Barnes. All have beed reloaded at least 2-3 times.

I feel like this is in my sizing die, although I loaded 50 rounds last week with no issues. What is the best way to trouble shoot this?
 
Is this a result of differences in the thickness of the brass in the neck? Maybe the problematic cases have very thin brass in the neck and the sizing die that sizes the outside diameter isn't producing a small enough inside diameter. If that's the issue, discard those cases.

The Lee neck collet die is easy to recommend because it is very affordable and it uses a collet to squeeze the brass around a mandrel. Regardless of what thickness the brass is, the inside diameter is correctly sized. There are other fancier ways to size the brass with a collection of neck bushings or Sinclair expander mandrels, but the LCD is simple and inexpensive.
 
D.B. Cooper said:
I feel like this is in my sizing die, although I loaded 50 rounds last week with no issues. What is the best way to trouble shoot this?
Click to expand...

I would disagree and be looking at the brass.

There are two parts to this issue. The brass and the die. The die is static, it will not change dimensions. The brass is fluid and will change dimensions. You have also stated that you have reloaded this brass 2 to 3 times before with no problems so what has changed? Same die?
 
I had that happen with a 257 roberts neck size die. I pulled the mandrel, chucked it in a cordless drill, and spun it against some 400 grit sandpaper to turn it down just a tad. Worked great after that.
 
If you are using a full length sizing die, I suggest full length sizing which includes bumping the shoulder back about 0.002”.

If using a neck sizing die, I agree with the cleaning comment.
 
D.B. Cooper said:
I processed them all the same way at the same time. Some RP brass, some Barnes. All have been reloaded at least 2-3 times.
.....What is the best way to trouble shoot this?
Click to expand...
It seems to me that using mixed brass with different numbers of firing is causing your issue. Firing the rounds and sizing the cases causes work hardening which leads to spring back. Some cases spring back more than others.

I tried the Lee Collet Neck Die and ran into the same thing as you describe. If you want to continue using the Lee Collet Neck die, I suggest sorting your brass by Head Stamp and number of firings, and consider obtaining an undersize mandrel and pin gauges to check the inside diameter of the sized case neck.
 
I agree that segregating by headstamp is a good first step. If you find that all of the "problem" cases are of the same brand...

I also would measure the expander ball. They often are a bit larger than ideal, undoing some of the good work done by the die. Combined with work-hardened case mouths, that sometimes will give the results you've experienced.
 
D.B. Cooper said:
So. I'm having problems with neck sizing/neck tension. I just ran 50 cases through my Lee sizing die. Trimmed to length. Deburred. Out of the 50, 12 are so big that there is no resistance on the press lever when seating. The projectiles almost fall right through. (On 2-3 cases, the projectiles will fall right through.) I dumped the powder out of three of them, decapped, and resized. Of the three, one would take a projectile properly.

I took some measurements and found that the cases that won't take a projectile are .240+" and the ones that worked have an ID of 2.35 or less.

I processed them all the same way at the same time. Some RP brass, some Barnes. All have beed reloaded at least 2-3 times.

I feel like this is in my sizing die, although I loaded 50 rounds last week with no issues. What is the best way to trouble shoot this?
Click to expand...
I don’t see anything about annealing or de-stressing the brass. I think you may be seeing spring-back, the results of work hardened brass. Of course, I could be wrong and the usual experts are bound to disagree. Just a suggestion of something to look for.
 
GeoDudeFlorida said:
I don’t see anything about annealing or de-stressing the brass. I think you may be seeing spring-back, the results of work hardened brass.
Click to expand...

Along with knowing wall thickness in the neck, it would be helpful to measure “sized OD, with AND without the decap/expander in place. The “without” would tell us if the die is capable of sizing a case correctly, without the expander being part of the equation. The with would give us an idea of the expanders role.

Also, what Lee die exactly are we talking about? With some of them, the above is null.

What case lube and application method are you using?
 
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Are you using some of the same box of bullets you have used in the past that worked OK? A new box of bullets might have impropperly sized ones in it. That combined with a minimally sizing die or an overly sizing expanding die and you have problems. If you remove the expanding mandrel and size your brass will the bullet fit tight? Something must have changed.
 
OK. So, first off, thanks to everyone for your input.

I have some things to try, but it will take me a few days to get back here with the results.

I did run some cases through the die with the de capping pin removed and got the same, oversized result. I don't think that's a complete test. Seems like there is another piece in there that has to come out. Not sure.

I've pretty much lost track of how many times each case has been fired. I used to track that, but it seemed (at the time) to be information I never used or needed, so I stopped recording it. However, most of this brass is 2-3 times fired Barnes. Some of it RP/Win range pick-ups. I also have about 400 pcs of RP and Win from yeaaaaaaars ago when I was competing. Most of that is 2-3 times fired as well. I almost wonder if I shouldn't just order a bag of new brass from grafs just to have a "control group." (Edit: Nevermind. New, unfired 243 brass cost as much as loaded factory ammo. I'll just shoot some factory Winchester ammo I have, if I need new-ish brass.)

I'll take some pre- and post-sizing measurements, and I'll sort the brass and get back here, hopefully by the weekend.
 
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You could take a few of brass that are working poorly and put them in a cake pan neck up with an inch of water in it. Then heat the necks evenly with a propane torch until they start to turn dark. Then let them cool. If they glow orange in a darkened room that is too much heat and will make them too soft though. That should anneal them enough for you to try resizing them again using a full length resizing die and see if your neck tension returns. If so it is time to anneal all of them.
I am still suspicious that last time you reloaded all with no problems and now everything has gone to crap. You are missing something.
 
Walkalong said:
Start full length sizing and forget the issues neck sizing can cause, cases will last just as long and accuracy may even be better.
Click to expand...

My thoughts exactly. A full length sizing will remove a lot variables. If the bullet still falls into the case then the brass needs annealing because it's too work hardened to stay properly sized. It doesn't matter what die you use when it gets to that point unless you go to a tighter neck bushing, which in turn just increases the stress on the already work hardened necks and shoulders.
 
Rule3 said:
Click to expand...

Not a fan of this video, seems like this guy really doesn’t know what he’s doing.

Annealing isn’t the problem or the solution.

If a guy really wants to know how much bullet hold/ neck tension he’s using then start by measuring the OD of a loaded round followed by sizing the neck down to a OD that represents a reduction in thousandths.
Example: .264 loaded round- resized to .261 yields .003 bullet hold.
 
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South Prairie Jim said:
Not a fan of this video, seems like this guy really doesn’t know what he’s doing.

Annealing isn’t the problem or the solution.

If a guy really wants to know how much bullet hold/ neck tension he’s using then start by measuring the OD of a loaded round followed by sizing the neck down to a OD that represents a reduction in thousandths.
Example: .264 loaded round- resized to .261 yields .003 bullet hold.
Click to expand...


First video that popped up.

With all the other threads by the OP on neck sizing, OAL, not trimming different brass I got nothing else:)
 
your neck i.d. will vary with wall thickness with that die. either make all the neck wall thicknesses the same, or switch to a full length sizing die. also, the collet limits the amount of sizing, so if the neck thickness is too small, tension on the bullet will be insufficient.

luck,

murf
 
How long is the case being sized. I often discuss dwell time for consistent sizing. I've never neck sized so I don't know or have no experience with that. I have watched the Lee die used and people seem to not use enough force to make it work.
 
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