Insufficient neck tension??

[Dave R]

I'm getting all confused here. I've been reloading for .380acp for a short time. Recently added a 2nd .380acp pistol (A P-3AT) and a 2nd type of bullet (Speer Gold Dots).

I resized and belled a bunch of brass last night. Found only about 10 pieces (out of 70) that had insufficient neck tension to hold the Gold Dots.

My Laser-Cast lead bullets fit in all cases. They mic at .3565

The Gold Dots would slide down those 10 cases with fairly little finger pressure. The Gold Dots mic at .355

I ran the 10 slack cases back through the resizer die, belled them again, and same result.

Ran then through again with the expander/decapper pulled up quite a way. Same result.

What could cause this?

-Chamber on one of my pistols is oversize and the brass got stretched?
-Resizer die is not "small" enough? Then why only a few cases?
-Expander ball is too big? Then again, why only a few cases?
-Too much bell? I adjusted it down to where I could barely insert the Gold Dots, and once they got past the (minimal) bell, I could still slide them down the slack cases. But not the others.

Thoughts?

 

[HSMITH]

Were those 10 a different brand? Remington and Federal are known to be thin, and thin brass with a sizer die toward the large side will cause what you are having. A simple solution is the Lee/EGW U-die, it sizes the cases down a couple thousandths more and eliminates the chance of too little bullet tension causing setback, and setback causing you to blow up a perfectly good gun. If you load mixed brass I strongly suggest U-dies.

 

[Dave R]

Those 10 were all IMI brass, which I thought was pretty good.

Most of the "good" brass was IMI, too. I do have some PMC brass, and all of those had correct neck tension.

So is the Lee/EGW U-die basically a small-base die?

 

[twowheel]

My experience with IMI brass is that it is thin and brittle. The thin case walls will make a big difference in inside diameter of the case.

I hope you are crimping those cases with a taper crimp die. That will cure the issues you site.

Twowheel

 

[Dave R]

Yes, I do use a taper crimp. I had been using a light taper. Always thought that you use the minimum necessary to keep the bullet from moving under firm pressure. The last batch where I had a few with insufficient tension, I increased the taper some. (Last batch, I though the few with insufficient tension were just some I had not run through my resizing die.)

I worry about using taper to do something that neck tension should be doing.

IMI brass is not so good, eh? I thought it was mil-spec, with thicker walls.

 

[HSMITH]

Proper taper crimping just removes the bell from the case, it does not increase neck tension in any way whatsoever. In fact, too much taper crimp will ruin any nect tension you might have had. Neck tension is the ONLY way to prevent setback.

 

[Dave R]

So for now I'm just using the "loose" cases with lead bullets. Neck tension is fine with those.

Sounding more like one of my pistols has a bigger chamber, eh? And why doesn't my resizer die bring back the neck tension?

Loaded some more Gold Dots with with (new) once-fired brass and had fine neck tension.

Still puzzled.

 

[dodgestdshift]

DaveR:

It sounds like you should try different brand brass. If you try different brass and it works ok, then ignore the rest of my answer, and don't use IMI brass. If the other brass has the same problem then try an experiment. After sizing the cases, but before belling, try to insert the bullet into the case with slight hand pressure. If the bullet goes into the case or worse yet falls through the neck, you have a problem with the case neck being too thin. If this is the situation, you should deep six the cases. If all case brands do this, your sizer die is not set right or there is something wrong with it. Call the die manufacturer for help.

If the bullet won't go into the case, before belling, the problem is with your expander step (notice not necessarily the expander ball). Now move your expander up so it doesn't touch the case, when the case is all the way into the die. Turn the expander plug down until you feel resistance. Remove the case from the die, and run it back into the die. The correct belling of the case can be tested by the following method. First look at the case, you should see expansion, but barely see it. If you take the bullet and insert it in the case it should balance in the case. If it doesn't, screw in the plug slightly, and run into the die again. Again you should barely be able to see the expansion of the case, and the bullet should balance. Keep going until this works.

Seat the bullet without crimping. Test the uncrimped cartridge, by hand, seeing if the bullet is tight. If not, try less bell (see above). If tight, crimp the cartridge. If the bullet is now loose, you are crimping too much, you should back it off some. Eventually you should find the right settings.

 

[Dave R]

Thanks, dodge. I'll try the readjustment process you describe.

I'm still puzzled, though...why would only about 10% of cases wind up that way? I would think if the die was adjusted wrong, all the cases would wind up the same.

 

[dodgestdshift]

You are right. Like I said, it is almost certainly the cases. The other info was, a good way to check adjustment of your expander and crimp dies.

 

[Bob C]

I had this problem with some Reminton .357 brass. After three reloadings, about half of the batch would no longer hold a bullet firmly enough in place for the crimp to be applied.

I've since switched to Starline brass, and haven't had any further problems.