Sizing small pistol shells

[brselman]

I admit I am very new to reloading, but I am having an awfull lot of fun doing it for both 9mm Lugar and 40 S&W cartridges. The fun way outways time. At any rate can anyone realy tell me if trimming shells prior to charging is important for both calibers? Is there a practical performance difference between using Unique or Accurate #5 powder?

[Leftoverdj]

If you don't resize the cases, the bullets fall out.

You can use AA-5 where you would otherwise use Unique. There will be minor differences in charge weight and results so you can't simply substitute one for the other, but you can get about the same results with either.

[brselman]

Sorry I meant trimming not sizing (Mea Culpa!). Thanks for the tip on the powder.

[jclaude]

I have never found the need to trim 9mm, 40 S&W or 45 ACP. I have loaded and fired many thousands of them. The magnum cartridges, .357, 41, 44 Mag, etc are a little different. I do trim them on a fairly regular basis. Even 38 Spls on occasion.

There's not much difference in Unique and Accurate #5 from a burning rate perspective. I think they are very close to each other on the burning rate scale.

[918v]

Except that Unique will give you better accuracy in the 9mm. Trim your cases to the same length if you like stuff like a consistent crimp. If you don't care or your brass is within .001" of the shortest piece, then dont trim. Some brass, such as RP, varies by as much as .009" and this will cause excessive crimp on some and not enough crimp on others. You only have to trim once. Pistol cases don't stretch unless you load them to 60000 PSI.

[jclaude]

From my experience with them:

Pistol cartridges that are normally taper crimped (such as 9mm, 40 S&W, & 45 ACP) don't seem to be nearly as suceptable to performance variations from minor case length differences.

Not saying it's a bad idea to trim them, just hasn't seemed worth the time and effort for the little bit of benefit to me.

[brselman]

I want to thank everyone who has responded. It has been very helpful. Indeed, these forums are very informative and fun to read.

[WESHOOT2]

too much :barf:

Pistol cases stretch with each firing.

[918v]

Really,

Why is it that my pistol cases don't? Maybe I have magic cases? Maybe I'm a reloading god? What could it be?

I've been trying to get them to stretch so that I could have some decent-length 9mm brass (factory is .010" short), but they just won't stretch!

Wee,

Please help. What is your secret?

[jclaude]

Pistol cases don't stretch unless you load them to 60000 PSI

Pistol cases stretch with each firing

Hummm! Is it possible that the truth lies somewhere between these two diverse positions? Maybe!

[caz223]

My pistol cases have never needed trimming, nor do they stretch after firing.
Now, my REVOLVER cases do stretch.
It has to do on where the case headspaces.
Since auto pistols (Excepting bottleneck and rimmed.) typcally headspace on the case mouth, and the mouth expands, how CAN the brass stretch, esp. if you don't roll crimp auto brass?
Now, revolvers stretch brass, the magnum class with H110 for powder has always has the best luck with a heavy roll crimp, and the bullets typically used are very strong and resist deformation.
The brass is held from being pulled FORWARD at the REAR of the case (The rim), and before the crimp lets go it pulls the case forward.
Since it has the whole case to stretch out, and lots of time to do it, the revolver brass typically stretches, you have incipient case head seperations, and the necks get brittle from work hardening (Being crimped, belled, crimped, belled, etc doesn't help, either.).
Auto pistol brass tends to be tapered (9mm), taper crimped (almost everything.), uses faster powders, and headspaces on the case mouth, and as a result, I've never seen any auto pistol brass need trimming. My auto pistol cases have exhibited different types of failures as a result. More case failures (Splits that run from the neck down 1/2 way to the case head.). Loose primers. 6 o'clock bulge. (Revolvers don't have feed ramps, either.)
YMMV.
As a matter of fact, most auto pistol brass is TOO SHORT.
As a result, it doesn't headspace on the case head, but on the extractor, and you're just not getting all the accuracy you could be.
Now, I admit, the cases MAY stretch while BEING RESIZED, EXPANDED, or CRIMPED, etc, but not enough to cause problems during the service life of the brass, unless you're doing something exotic.

[jclaude]

CAZ223.

Your position closely mirrors what I have have been saying about stretching/trimming of revolver vs pistol brass.

There is, however, one little caveat to your reasoning with the non/stretching pistol brass. When the pistol case obturates against the walls of the chamber, it probably gets a little shorter, if there's any change in the case length at all. The potential for the growth of length of the case comes not from the firing process but the resizing process. Remember that the outside diameter of the case, after firing, is now larger than it was before firing. (That's why you size it, but you know that) When you resize the case back down to or just under new case dimensions, where does or can that extra material go??

The bottom line is this: If the length of your cases (pistol or revolver) causes problems for you, or if you just like to trim your cases, by all means, trim 'em.

If neither of those conditions exist for your application, why bother?

[caz223]

That would depend on the smoothness of your cylinders (And you know, dozens of other factors, including the prevailing wind and whether your mouth was open when you were shooting.)
I think we agree more on the issue than disagree.

It just pains me to hear someone knowledgeable and respected go against my experiences. (Not you jclaude, someone else.)
Any time you work metal, it stretches.
But that being said, I have fired the same 9mm cases 20x and they were STILL not at trim-to.
I can't remember if they stretched, or how much, but I did this many years ago.

[caz223]

Most the the early experiments in case prep involved a lee loader due to the low numbers of brass, and the need for portability.
I noticed a trend wth lee loaders, due to the WAY the brass was belled, there was no stretching on ANY caliber, .41 mag was my main test subject.
But I didn't crimp, my work hardened brass after being loaded soooo many times didn't need it any more. The neck tension was awesome.

[WESHOOT2]

Cases stretch upon firing; some get longer, some get shorter, some stay the same length; all stretch.

[caz223]

*Scratches head*
I suspect we're mostly in agreement, and we still find things to argue about. *shrug*
That's my story, and I'm stickin' to it.