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Old September 9, 2009, 10:38 PM   #1
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.223 Case trimming

I know the trim length of .223 is 1.750" and the max length is 1.760".

I recently got a Dillon Rapid Trim 1200 and a spare tool head to mount it in. It is now faster to just run the brass through the trimmer than it is to measure each piece and decide to trim or not to trim.

So my question is this:

If you were to trim the brass EACH time you loaded it, where would you set your trim length?

I'm thinking somewhere in the middle. 1.753" or 1.755". I'm curious to hear any other thoughts and the reasons why.

Thanks in advance.
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Old September 9, 2009, 10:42 PM   #2
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Trim to min trim length 1.750" as there will be variances case to case. But, the more consistent the OAL the more uniform crimp you can apply if you choose?
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Old September 10, 2009, 09:52 AM   #3
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I normally measure all my brass first and then trim them to whatever the shortest case I measured. So if the shortest one was 1.753 I set my trimmer for that length so they all come out the same. Of course if I find a couple at say 1.744 or so I don't consider it for my gage. It has to be 1.750 or above.
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Old September 10, 2009, 10:48 AM   #4
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I trim all my .223 to 1.750. Even on the rare occasion I purchase brand new brass, it gets trimmed as well. You would be surprised at the case length variance on new brass! I also trim everything that has been shot, even if it's once fired brass.
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Old September 10, 2009, 04:38 PM   #5
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I trim every time also

same as BigV. It just works out easier and more consistent than measuring and guessing. Shoot 100+ shells, measure them, each comes out different in some way with a factory chamber. I don't re-size new stuff though It's a waste of time to me. But I 3-way trim each time with the RCBS tool.
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Old September 10, 2009, 09:52 PM   #6
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As long as you are within the 1.75-1.76 range, it doesn't really matter if you plan to trim every time you reload. Most people don't trim every reload, thus the range that is stipulated.
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Old September 11, 2009, 03:38 AM   #7
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I got brass thats 1.74 could that be used? Or is 1.75 the min.?
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Old September 12, 2009, 09:27 PM   #8
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Your 1.74 brass can be used.
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Old September 12, 2009, 09:53 PM   #9
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The actual SAAMI spec is 1.760" +0/-0.020". So anything from 1.740" to 1.760" is within that spec. The long number is to prevent the case mouth going deep enough into the chamber to jam in the throat and raise pressure. The short number is so the smallest bullets made still seats deeply enough in the case to have adequate neck tension on them for magazine feed without the bullet being knocked too far off axis if they are seated within the SAAMI max cartridge COL. Still shorter bullets can be used, but often have to be seated below maximum COL, and the manufacturers usually give you the reduced COL in their load data.

The trim length is usually in the middle of the SAAMI range to allow for some plus and minus tolerance error in the trimming. The fact is there are people who trim much shorter than even 1.740". If you don't crimp, you can often get away with that. The advantage is you can trim the case just once and never have to trim it again within its normal case life because it will just grow to 1.760" about the time neck splits or other wear problems cause you to retire the case altogether.
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Old September 12, 2009, 10:08 PM   #10
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I trim all rifle brass to min trim length. EVERY TIME

Is it absolutely necessary? Probably not but it make me feel better. You can do the minimum amount of prep or go above and beyond. How accurate to you really HAVE to be?
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Old September 12, 2009, 10:46 PM   #11
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I trim first time I put the brass in use. MOST commercial brass is long. I just fired some South African surplus (DNL) and some Greek Olympic, and both measured 1.765-1.77 after first firing.

But then it doesn't need trimming again for 4-5 reloadings. I measure after I resize, and I find it takes several firings for them to lengthen enough to need trimming again.
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