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Old April 10, 2017, 01:22 PM   #1
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Trimming cases

As I read posts here I see that most everyone trims their rifle cases but I keep seeing that people don't trim pistol cases. I can understand in a straight wall rimmed cartridge there is less need to trim but the length can affect the amount and quality of the crimp. In rimless cases The length of the case is important to the chambering of the round. Too short and it might not fire and if it is too long it may not chamber.
I also hear that straight wall cases don't grow. I can testify that they do grow and some a lot more than others. For example, in my 9mm, using Blazer Brass factory loads most of them will trim after the firing of the factory loads. I should point out that my trimmer is set to the maximum length and not the "trim to" length. I do that because I run all my brass through the trimmer rather than using calipers to first check the length and then trimming the long cases.
I am wondering if it is just something that happens to only me or is it just ignored by others. I get cases that trim in each batch of fired reloads.
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Old April 10, 2017, 01:37 PM   #2
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Must be you. I've been shooting .357mag, 44mag, 9x21, 9x18, and a host of others for close to fifty years. I haven't needed to trim any yet. Some have been shot at least ten or twelve times and still crimp very well in the bullets that have crimp grooves and the ones that don't seem to shoot and work well in my semi autos. I have trimmed them in the past years ago to see if it made any difference in group didn't, so I didn't do it again. They get a bit shorter when fired and get longer when is normal. Bottle neck
rifle brass gets trimmed with some frequency.
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Old April 10, 2017, 01:47 PM   #3
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I agree with NSB. I started handloading in April 1963 and I have never trimmed straight wall handgun brass.

Most times with cartridges such as 45 ACP, 40 S&W, 9x19, and so on the brass gets changed over quite a bit as I lose some each outing. No matter how hard I try, some get lost.

Not so with the revolver brass. I have never had a problem with crimps as I have learned to crimp by feel rather than by mechanical means of setting a die to a certain length. My crimping revolver brass is very consistent.

Works for me.
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Old April 10, 2017, 01:55 PM   #4
T. O'Heir
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"...they do grow..." No, they don't as much or as fast.
In any case, trimming bottle necked cases is an 'as required' thing only. It's not done every time. If the case is shorter than the max case length given in your manual it does not require trimming.
It will take you far less time to set your calipres at the Max case length for whatever and use it as a gauge.
" trimmer is set to the maximum length..." Don't. Set it to the Trim-to given in your manual for a reason. Even though you don't need to trim if the thing is shorter than .754".
For example, a 9mm case's max length is .754" -.010. That means there's a 10 thou tolerance. If the case is .744" to .754" long it's fine.
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Old April 10, 2017, 02:32 PM   #5
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I keep all my brass whether for rimmed or rimless cases. I use a brass catcher for my semi-autos and the revolver and bolt action cartridges are placed back in the box after being fired. I don't believe it changes anything as far as accuracy goes. I am more concerned that long brass might pinch the case around the bullet if it was too long or just fail to go into battery. Since my trimmer is set for the maximum length the cases will never be longer than that when fired as they go through the trimmer whether they trim or not.

What I do has worked for me for the last 45 years so I am not likely to change the process now. As long as I see some of the cases trimming it just reinforces the need to do it. (for me)
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Old April 10, 2017, 02:53 PM   #6
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Straight walled pistol brass can change shape after being fired.
Sometimes shorter, rather than longer - the results of brass wall thickness and chamber dimensions variances.
The resizing pretty much corrects it.
So I've never bothered trimming pistol brass.
Precision pistol shooting might benefit from it, though.
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Old April 10, 2017, 02:58 PM   #7
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When I was a more active reloader I found that firing my .357 reloads out of a variety of revolvers made trimming necessary.
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Old April 10, 2017, 03:21 PM   #8
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I trim all rifle brass, and any pistol brass that uses a roll crimp.

For taper crimped auto pistol calibers, no need.

Sometimes I use 45 ACP bullets in my 45 Colt, I taper crimp those and skip the trimming since it's a non issue in that use case. But with 45 Colt bullets, I do trim them to uniform length and roll crimp.
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Old April 11, 2017, 11:38 AM   #9
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I have had straight brass stretch enough to have issue with some of my revolvers which I have more years reloading for. I got into automated machines which trim the brass so it was too easy to do it than even think about it. But I did have some bind in my revolvers before getting involved in trimmers.
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Old April 11, 2017, 05:13 PM   #10
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I trim both my .357 mag and .41 mag so that I get a nice uniform crimp. I do this because I also shoot them in my lever actions and like a nice solid crimp. I don't bother with .38 and 9mm since I just remove the belling on .38's and taper crimp my 9mm. On the magnums once I trim them they seem pretty much good for the life of the case. I also use the Lee collet crimp on the magnums, very easy on case life but a very strong effective crimp.
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