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Greetings to all! I am new to reloading and am about to load my first batch of .40S&W for my Beretta 96. I read in the Lyman Reloading Handbook (49th ed.) that the case length spec is 0.850", and that the Lyman-recommended trim-to length is 0.845"; they recommend discarding cases shorter than the trim-to length.

I have a brand-new bag of Winchester .40S&W cases to which I took my digital dial caliper to check lengths. All cases range from 0.840" to 0.845"; nearly all are under the Lyman-specified minimum length. This leads me to a few questions.

1. Is Lyman correct in the 0.845" minimum length? I don't have any other references, so can't cross-check. 0.005" seems like a really narrow range to me.

2. Are the Winchester brasses defective?

3. Given that I'm firing a non-target pistol and am still leaning to shoot well, should I worry about trimming all cases to a consistent length or is a +/- 1-2 thou length going to prove satisfactory? I am concerned that too-short cases can create overpressure issues.

Many thanks in advance to all...this forum looks like just what the doctor ordered for a newbie like me.

Walt
El Cajon, CA USA
 

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My post appears to be lost.
Oh well...
1. Is Lyman correct in the 0.845" minimum length? I don't have any other references, so can't cross-check. 0.005" seems like a really narrow range to me.
Measure AFTER sizing.

2. Are the Winchester brasses defective?
No

3. Given that I'm firing a non-target pistol and am still leaning to shoot well, should I worry about trimming all cases to a consistent length or is a +/- 1-2 thou length going to prove satisfactory? I am concerned that too-short cases can create overpressure issues.
Pressure is a function of the case volume after seating a bullet. This is NOT effected by the trimming of a case. You are sweating a non-issue.

Straight-wall cases have always been supplied too short. With several reloading cycles, you will find that many straight-wall cases will actually shrink. Do not trim straight-wall cases that headspace on the case. Trimming will ONLY cause an increase in headspace. Check your manual for what they say about excessive headspace.

The two least important areas and the two areas that newbies seem to fret about are trimming cases and case crimp. Read the manual.
 

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I have NO idea why Lyman and others continue to even talk about case length for straight-wall pistol cases. They don't grow like bottleneck cases and, as you found, are almost always way to short.
Think about this: for best accuracy and function, you want to minimize head space.
If a case that is 0.850" has only 0.001" of headspace, then look at the headspace your new cases will have. No wonder so many rounds are actually held by the extractor.
Next, if you are going to worry about case length, measure AFTER sizing. Yes, even new cases should be sized.
 
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