Case mouth crooked

[bigtony]

I was priming some R-P 9mm this morning and noticed a couple shells sitting crooked in the reloading block. Pulled them out to measure and they were about .010 +/- difference in length from one side of the case to another. Case mouth was cut crooked. All factory shot brass. Never had this with any other brass. I'll just either trim them down if there is room or toss them if they end up too short. Wondering if anyone else has had this?

 

[918v]

All brass is crooked like that, maybe not by .010", but crooked nevertheless. If you want nice and even, you have to trim it and even then it won't be perfect.

 

[bigtony]

All brass is crooked like that, maybe not by .010", but crooked nevertheless. If you want nice and even, you have to trim it and even then it won't be perfect.

I understand nothing is perfect, but that is a huge difference on a small case (this was factory loaded brass). I reload alot of different calibers and none of them have ever been that far off. Also I've never had to trim a piece of pistol brass cause the mouth was so crooked. I went to get a good measure on it and the short side is .010" under trim length while the long side is .010" over. Thats a .020" difference.

 

[cheygriz]

Unless you're loading them for match competition, don't worry about it. You'll never notice the differencve in "plinking" ammo.

 

[918v]

In my experience, R-P 9mm brass length varies by .020". If you want better consistency, get some Winchester or Federal brass.

 

[Hondo 60]

I haven't notice such a difference, but then i don't trim pistol brass, so i never measure it.

 

[PO2Hammer]

Usually you can find around .003" difference or so on factory brass.
.010" or .020" seems excessive.

 

[bigtony]

I usually don't measure either but these were noticeable enough to really see. They should still seal tight for plinking loads but not for anything more. Just really have never seen brass that far off.

 

[918v]

Usually you can find around .003" difference or so on factory brass.
.010" or .020" seems excessive.

Not really. Try measuring all around the circumfrence of the case mouth and find the longest length. Then compare that to the shortest point on the shortest case. It is not unusual to see a .020" difference.

Because case mouths are uneven, five people measuring the same case can come up with five different readings.

 

[ranger335v]

It won't matter. The case mouth is expanded hard against the chamber wall before the bullet gets clear.

 

[918v]

It does matter. A 9mm chamber is supposed to be .762" long. Most brass measures less than .750" after sizing. A 9mm case measuring .730" now has .030" of excessive headspace. There's your flier right there. That bullet will surely impact away from the rest.

Several years ago Jim Taylor did an accuracy test that basically indicated .750" or longer cases produce better accuracy than shorter brass:

http://www.leverguns.com/articles/taylor/9mm_reloading.htm

 

[Taroman]

I had a batch of new W-W .44 special that had crooked mouths. In addition, they were below the SAAMI minimum length on the low side. Winchester sent a label to get them back.

 

[ranger335v]

"It does matter. A 9mm chamber is supposed to be .762" long."

Bigtony's question wasn't about case length --- "Case mouth was cut crooked."

 

[murf]

bigtony, my concern would be that .010" over length case. since the 9mm headspaces on the case mouth, that over-length case may not let the round chamber completely, or the case mouth may extend into the chamber and affect chamber pressure. you may want to trim the case first.

murf

 

[918v]

Bigtony's question wasn't about case length --- "Case mouth was cut crooked."

I knw what the question is about. Apparently you don't.