Case sizing help please.

B

Ben56

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I'm a basic shooter trying to get better. I have been reloading for many years but have very limited knowledge. I have been experimenting with my sizer die. If I leave the expander ball out of the die, the case neck seems perfectly concentric, put the expander ball in and I get a bit of wobble. I'm sure my first problem was buying the tool that tells me this! The concern with sizing without the expander is neck tension. With the expander, my inside neck dimension is around .305 (this is .308 by the way). Without the expander, inside dimension is around .298. Can I have too much neck tension? I appreciate any information or opinions.
 
One piece dies generally size case necks too much, so that when the expander is pulled back through, excessive pull causes case shoulders to yield slightly, asymmetrically, cocking the neck. There are several ways to approach solving this problem. A couple are, polishing the expander ball (without reducing its diameter), doing a little brushing of the inside of case necks (but not taking all of the powder fouling out), and lubricating the inside of necks (Imperial makes a dry lube that helps and does not require removal. Dip the necks before lubing the outside of the case.). There are other ways to solve the problem that involve buying a different die or dies, but the methods that I have outlined should help with your current die. Another thing, slow it down when pulling the neck over the expander. This will reduce the peak pull. In the past, I have had no problem loading for tuned up factory varmint rifles so that groups were under half inch, using dies like yours. This was before I had a concentricity gauge. Back then, my only gauge was a target.
 
Besides what Boyd said there's this.

Neck expanders cause neck runout, simple as that. If your die is sizing the insides of the necks to 0.298" and the expander is opening them back up to 0.305" not ending up with quite a bit of runout would be a near miracle. The solution is to get a bushing sizing die from Redding or Forster (since you can get bushings in 0.001" sizes instead of 0.002"). You need a bushing that will size the necks to 0.002" smaller than the neck diameter of a loaded round. Say that the OD of the loaded rounds is 0.334" (it'll vary some due to differences in neck thickness from case to case) then you'd need a 0.332" bushing to size the necks enough to hold bullets well. To be safe I'd order 0.331, 0.332, and 0.333 bushings along with a carbide expander button that should just barely touch the insides of the case necks when it comes back out through the necks. Redding's carbide expander floats on the decapping spindle so the chances of pulling necks out of line is minimal. This isn't going to be perfect, nothing is, but it'll be a lot better and cases will last longer due to less working of the case necks.

The alternative is turning the case necks, which is a pain in the tail unless you're shooting Benchrest. If your case necks vary widely in thickness from case to case or around the case necks it would be a good idea to sort cases by neck thickness consistency on the individual cases and from case to case.

For live varmint loads I don't turn necks unless the rifle's chamber requires it, and use the method outlined in the first paragraph with good results.
 
Use neck sizing dies that use bushings and don't use the expander. Use bushings that size the neck OD 0.002-0.003 under the OD when loaded. This has worked for me for many years.
 
Thank you Mr. Allen. It did not occur to me that the shoulder was being pulled off center. I will polish the expander ball as you suggest. Can bullets be seated in a case with a neck that tight without problems? Seems like most of what I'm reading says neck sizing needs to be about .002 to .003 smaller than bullet diameter. Would .010 be too much neck tension?

As to other dies, I am shopping. I'm trying to understand the what and why as I go. You guys make it sound easy, now I have to read an hour to comprehend...but I do thank you.
 
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I take the expander ball and the rod it is on out of the die and chuck it in a drill .
I use a very fine sand paper and a then a polish like Flitzs .

I also lube the inside of the neck just a little .
 
IMO .010 is too much. Here is another way to go. Some time back, I was sizing some .22-250 brass with a conventional FL die such as you have. The previous owner of the die set had turned his necks so that the ID of necks sized with the expander would work, but not wanting that much clearance in the chamber, and having been able to meet my accuracy goals for varmint shooting with unturned necks, I looked elsowhere. Since the fellow had turned down the expander ball so that it was only retaining the decapping pin, and had secured it to tightly that I could not easily remove it, I decided to use the expander die and mandrel for turning necks. It worked better than I would have expected to, leaving me with fairly high neck tension that was within my tolerance for difference in diameter. As far as the comment on shoulders, I did not mean that the shoulder would be pulled off center, but that it would be stretched out of shape a little, more on one side than the other so that the neck would be canted at an angle to the CL of the case. If you play around with a concentricity gauge, I think that you will see that runout increases the farther out on the neck that you go, and that even with the best seater, the bullet will follow the neck, showing an increasing runout the farther from the shoulder you go. A seater can't fix the neck, but it can make the situation worse as the bullet is seated.
 
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OK now I have a question .
Shooting a 223 with a tight chamber . The chamber neck is 2.047 the loaded round neck is 2.048 .

Do I need to turn it a little ?
 
I should say so, since you apparently have a .001 interference fit. What do you do, chilll the ammo and heat the chamber? Seriously, depending on the clearance you want and the largest diameter of the bullet, you should be able to arrive at the thickness that you need to turn to. If I wanted a loaded total clearance of .002 (.001 per side) and the pressure ring of the Flat base bullet was something like .2244, (and assuming that you meant to write .247 for your neck diameter) I would shoot for a neck thickness of around .0113, and would not get excited if the average was slightly more or less.

Added later: I must have been tired or something. Two times .113 plus .2244 is .247. To get to .245, what you need for loaded round neck diameter for a .002 total clearance , the necks should be .0103. Sorry about that.
 
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I`ve found useing a std RCBS, Redding, etc sizer with expander ball I get the same runout troubles the OP found.
I now decap with a universal decapper, FL size with the expander removed, and then re-install the expander stem leaving it high in the die and a hair loose and then run it in the case neck just enought to open the neck up for the bullet.
I know this still leaves the ID of the mouth sub optimum for my bullets diameter, but the runout is now zero on a seated bullet measured ~ at the spot the ogive reaches full bore diameter. I also lube case mouths every 5/6 pieces with Imperial, the same lube I use on case bodies.
 
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