Pistol Cases Getting Shorter not Longer?

[RGMJ]

Hi Guys,

I reload / shoot a lot of pistol rounds 9mm, 40SW, 10mm, 45 ACP in semi auto pistols.

I find the cases getting shorter the more I reload them.

This seems strange as rifle rounds get longer.

What gives? Am I missing something?

Thanks for your replies....

[Ford SD]

Hi Guys,

I reload / shoot a lot of pistol rounds 9mm, 40SW, 10mm, 45 ACP in semi auto pistols.

I find the cases getting shorter the more I reload them.

This seems strange as rifle rounds get longer.

What gives? Am I missing something?

Thanks for your replies....

All of the above cases head space on the mouth of the case

the hand gun cases that seem to stay the same length till they split are the cases that head space on the Rim 38/357 etc.

the 45ACP is a low pressure round that the brass seems to last forever
when you can barely see the headstamp the brass could be 0.040-60 thou short and will some times still function in most guns
(practice rounds I call them) because you some times have to practice clearing jams

Also the other fact is that rifle cases work at a higher pressure
the exception (some times) is the cast rifle loads where you might get 4-5 up to 10 loadings to strech enough to require a trim for length

[popper]

No expander plug to PULL the brass longer. I was at a retail store and the sales guy was trying to sell a trimmer to a noobe for pistol reloading. They get SHORTER, no LONGER.

[Old Caster]

Not all straight pistol brass gets shorter with use. Most 32 S&W long cases will get longer with use but some will get shorter. This happens even with all brass from the same manufacturer and shot from the same gun. If a larger sizing die is used the change in length will lessen in both directions and I have no idea why. This experience is with a semi auto 32 and I don't know whether it would be different in a revolver but it might because the 32 autoloaders have a large chamber for reliability and for a revolver it wouldn't be necessary to be oversized. -- Bill --

[MtGun44]

Straight cased auto brass seems to get shorter, shouldered brass gets longer due to headspace.

Bill

[runfiverun]

might just could be from the die pushing down on it when resizing.
nothing ever pushes forward on the case.
maybe we should roll crimp them??

[Old Caster]

RFR, In the case of the 32, even when sized with a .002 oversize sizing die, they have to have a .314 expander shoved down into the case as long as the wadcutter is that will be installed or inaccuracy will result and it puts a strong pull on the case when extracting it. Case trimming is very important to keep bullets from tipping because one side can be longer than the other and crimp will also vary a lot. When I was shooting from a stock barrel that was .314 with a large chamber, the brass grew a lot except for a few that got shorter. After changing to a barrel with a .312 bore with match chamber and downsizing my expander to .312 the brass seems to change more slowly. My minimum I will use is .909 and I trim at .911. After a lot of shooting, only about a half of a dozen pieces are .909 or less with the shortest at .907. Others in the group will get up to .915 in a few shootings and get trimmed again. This is new stock Lapua brass that was if I remember correctly from .910 to .919 originally. I only measure brass after resizing because it will be a bit longer after sizing. With my original barrel I used a roll crimp because a taper was not as accurate nor was it as reliable. Now, I have to use a taper crimp because it is completely unreliable with a roll. There is talk among the 32 crowd that when using a taper crimp, length is not nearly as important and time will tell if I experience the same thing. This all shows that until you try something not many truths are set in stone. I have no idea what length any of my 45 brass is nor do I care because the accuracy is the same if I use the same manufacturer of brass or mix them completely up. Some time ago when I was doing entensive testing in a Ransom Rest on a Les Baer 45 ACP wadgun I used only WW brass that was new. After reading on the Magnus site that they used mixed brass and got great results I had to prove to myself that even though their results were good they had to be better with perfect brass because it sure is important when shooting benchrest rifle or even a pistol like a contender with a rifle caliber. What I found out finally is that it didn't matter in a 45 ACP but this is probably the most forgiving caliber there is for handloading. -- Bill --

[popper]

I suspect rimmed pistol cases could stay the same or get longer.

[felix]

Cases get shorter and/or longer depending on deformation characteristics caused by the directions of pressure, such that the directions are either internal or external when the elastic limit of the cases are surpassed. For example, a new bottle necked case shooting a 65K load will get wider first (shorter), and then narrower (longer) before ejection because of the barrel springback. That same case will become shorter after a 35-40K load, provided the previous hot load did not permanently alter the elastic limit value. And then, shorter and shorter with continuous cast boolit shootings until stability is reached. Donuts must be verified to not form for about the first three cast shootings. Changing the gun chamber(s) and/or the brass, via anneal, causes very erratic case behavior from then on. Thus, BR folks seldom anneal match cases and purchase/prepare new ones instead, and most likely for a new barrel at the same time. ... felix

[dillonhelp]

In a straightwall case, molecular compaction casues the case to get shorter with use. Several years ago Handloader magazine ran an article about this. On bottleneck cases, brass flows towards the case mouth, and the resizing extrudes it, making the case longer.