Skipping case-mouth expansion

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Scott Bear

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if you are not loading a soft lead bullet in a straight-walled (45-70, .45 ACP, 9mm) case can you skip this step?

Why is it all in one die (decapping and neck expansion) for bottle neck cases?

Thanks,

Scott.
 
With a boatail bullet you could skip it, but most straight cases don't use bullets like this.

The reasone you can expand and size in one die on bottleneck cases is the expander is down in the larger part of the case when the neck gets sized. It is then dragged back through on the downstroke to open up the neck (expand if you will) to 1 or 2 thousandths smaller than the bullet. So a .308 case might be sized to .305" and the expander pulls back through expanding the case to .307" for a nice tight fit.

In say a .45-70 if you had a .457 expander in a sizing die it couldn't be pushed down most of the way in the case and fit while sizing/depriming.
 
This is funny, I was just wondering the same thing a hour and a half ago. As my expander is set to nearly nothing I figured I'd give it a try. I dont see a difference in the finished ammo nor does my caliper. I'm loading 9mm by the way. Neck flare looks and measures the same. I am using ordinary 124 gr berry plated bullets and I have to hold them until the nose is in the seating die but that is no different than I did before.

Hope that helps
 
The only reason to bell the case mouth in straight walled cases, IMO, is to allow bullets...specifically lead bullets, to start into the case without shaving lead or crushing the mouth.

As long as the case mouth is not "crushed" for being too small or from having a too small bell for the bullet base to start, only a minimal amount of belling is required for flat base bullets. Bevel base bullets do not need as much belling or flare.
 
I take down the expander ball with emery and stone it smooth so it will take out any minor dents in the case mouth but doesn't have to be dragged through the neck. I've always felt that the tension by a standard expander ball works the brass unnessesarily. I have never had a problem with this system even with flat based bullets.
 
I have only loaded magnum pistol cartridges but for my first several thousand rounds I pumped out I never bothered flaring cases I was putting jacketed bullets into. I only do now because I have grown picky and particular about the ammo I make...
 
I have been reloading eight handgun calibers and four rifle calibers for many years with out ever case-mouth expanding for any of them without any problems. That being said here is what is done to circumvent the mouth expansion step:

* a very generous chamfer to the case mouth, a one tme operation.
* use of only bevel base bullets for cast pistol bullets.
* use of only boat tail bullets for rifle bullets, these perch much eaiser on the case mouth than flat base bullets as well.

The above three points will eliminate the necessity for mouth expansion, and the cases will last much longer as they are not being continuously worked by expansion/crimping.
 
mmattockx:

I'm only loading for .45 ACP at the moment, but reading the ABCs of reloading it shows bottle neck rifle cartridges have only two dies. The decapper/resizer die has a flare to the decapping pin that reforms the neck when you pull the case out of the die.
 
Scott Bear said:
mmattockx:

I'm only loading for .45 ACP at the moment, but reading the ABCs of reloading it shows bottle neck rifle cartridges have only two dies. The decapper/resizer die has a flare to the decapping pin that reforms the neck when you pull the case out of the die.
Click to expand...

The expander button goes through the neck into the body of the case, then pulls back straight out to set the ID of the neck. It doesn't flare the case mouth at all, that is a separate operation if it is needed. I can understand your thinking, the rifle dies work a bit differently than typical pistol dies, which don't have an expander button.


Mark
 
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