Trimming cases.

Reloading equipment, methods, load data, powder and projectile information.

Trimming cases.

Post by Stix » 05 Mar 2018, 11:26 pm

What do people consider is an acceptable case length difference in any batch of cases...? (Ie; 0.001"...0.005"....0.0005"...?)
And...
How far below listed trim length is acceptable/safe to trim to.?

The reason i ask is...
I had a new batch of cases where quite a number of them were well below listed trim to length (a good 15-20 or more were .010" under, & the worst few were .015" under).

They have been fired & FL sized to get some length back in them, but around 8/50 or so cases are still .004" under listed trim length, & the longest are now .005" over.
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Stix
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Re: Trimming cases.

Post by Apollo » 05 Mar 2018, 11:50 pm

Are you a target shooter or just a hunter/varminter..??

Many reloading manuals and or SAAMI Specs mention a Maximum case length and the trim length is 0.010" less than that...don't go under that length. Carbon ring story.

Pick a medium above the minimum case trim length, or the minimum and anything under....don't touch... They will/ maybe lengthen in time.

Don't go OCD... it's not that bad.

Many times new cases when they are fired will shorten, because they expand pulling the shoulder back but they will/maybe expand in the future. New cases will perhaps be short including top of the line Lapua brand.
Apollo
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Re: Trimming cases.

Post by Stix » 06 Mar 2018, 12:26 am

Hi Apollo..
Hunting/varmint.
Im not familiar with the tale of the carbon ring...?
The man who knows everything, doesnt really know everything...he's just stopped learning...
Stix
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Re: Trimming cases.

Post by Apollo » 06 Mar 2018, 12:29 am

Stix wrote:Hi Apollo..
Hunting/varmint.
Im not familiar with the tale of the carbon ring...?


It forms in front of a case neck if the neck is shorter than the chamber, the shorter the case neck the bigger chance of a carbon ring.

You have a PM.... I'm still up and about....
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Re: Trimming cases.

Post by wanneroo » 06 Mar 2018, 2:17 am

I have found there are always going to be slight production variances in brass which could affect overall lengths and then when you trim there is variance. Somewhere along the line someone came up with .010 less than maximum. Is that really what it should be for every case out there?? You decide. Especially for 308 Win I researched it online extensively. Max case length is 2.015. Conventional wisdom says min trim length is 2.005 and as I found tons of reloaders trim as far as 1.995 with no issue, even shooting in competition.
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Re: Trimming cases.

Post by Stix » 15 Sep 2018, 5:12 pm

Hey experts...Im back on this again...

In short, im running Win 308 brass in a 7-08...

Probably due to the sizing, the cases end up shorter than the listed trim to length for 7-08.

So trim to length is 2.025", however 50% of cases are at 2.019", with the remainder being down as short as 2.015".

So my question is, do I...
1)leave them until they have all grown to 2.025"...(this will take eeyons & give me random length cases).??
2) trim them to 2.019" and have approx 50% of the batch shorter than this length-down to 2.015"??
3) trim them all to 2.015", which is some .010" shorter than the listed trim to length.??

...And why...?

Keen to hear thoughts & theories/reasoning...
Thanks :drinks:
The man who knows everything, doesnt really know everything...he's just stopped learning...
Stix
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