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I have been loading for 223 with federal brass which are 1.750 in. in length after a full length size. Now I am running low on federal and will be using some lake city which are 1.760 in length after full length size. My question is does this make any difference in accuracy in terms of space for the powder or set depth of the bullet? I have a trimmer if the difference is crucial enough to mandate trimming. I have half inch 5 shot groups now and really dont want to screw that up due to brass that isn't uniform in length. Thanks in advance.:D
 

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By SAMMI specs the case trim too length is 1.750" with 1.760" being the point at which you need trimming. If you reload, shoot and leave the brass laying you could reload this brass. If you recover the brass for additional reloadings then you need to trim either this time or the next reload. I set my caliper to maximum length and check each case in the reloading block. If more than a few are at or over the 1.760" length then I trim all the cases keeping that batch uniform. Otherwise I substitute other cases for those few over the maximum length. This safely allows me one more loading before having too trim.

Answering you question about accuracy -- yes it can affect but its also dependant on other variables. The chamber on your rifle will be the most critical factor. Some don't like overlength cases while others don't matter. A tight chamber may restrict bullet release upon firing driving peak pressure to unsafe limits. While these may fit and work okay in your present rifle they may not work okay in another. Been there done that its not fun pulling, dumping, trimming then reloading again.

Short answer is too trim them before reloading.
 

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Pick up a Lee case trimmer, they are very inexpensive, and will last a long time.
 

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As a basic reloading rule, you should trim back all cases that are at maximum length, rifle cases especially.

While exterior case dimensions may be identical, interior dimensions may vary from brand to brand and sometimes even lot to lot so you need to develope a load with the brand of cases that you're reloading to obtain best accuracy. And then, you may not have to.

You will just have to trial some new cases with your old load and see.
 

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Adjusting the F L die to where you move the shoulder back just enough so they chamber easily , probably contributes to case longevity more than anything else . I trim F L sized cases just three times , then I chuck them out .
 

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When you fire a case, it expands, and when you resize, that extra resulting brass area has to go somewhere, so it squirts up into the neck, lengthening the case. If you let that go far enough, the mouth of the case eventually reaches the end of the neck portion of the chamber where the throat begins. Since it can't fit into the throat with the bullet, a neck beyond that length will jam into the end of the neck portion of the chamber, upsetting it and causing it jam against the bullet. This can raise pressure rather dramatically, as now the mouth of the case has no room to move aside to let go of the bullet.

The above hazard is what trimming is meant to prevent. The saws that trim commercial brass are not too precise, so the SAAMI spec spans 0.020" for the length of a .223 case, 1.740" to 1.760", and the saws try to hit the midpoint between those limits.

Does the trim length affect accuracy? Yes, but mainly it is a matter of them being all the same rather than hitting one specific number. The exception occurs if you are crimping the loaded rounds. At that point a length discrepancy can leave one crimp tighter than another, and trimming back more than normal can force the bullet to be seated deeper to get the crimp cannelure lined up with the case mouth for crimping. That deeper seating affects pressure and barrel time.

Some match shooters I know used to take the .308 and shorten it about 0.020" below the SAAMI minimum when it was new. Their idea was to get it so short it never needed to be trimmed again before they tossed it as too weak to continue being used. But they did keep all the brass together so the load history (number of reloadings with the same load) would be the same.

Consistency is the main thing. It should all be alike, whatever you did with it?
 

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I agree with these folks

I keep different brands of brass separate and trim as needed. Like another poster, after three reloads the brass goes in the scrap bucket. Brass is cheap. All the best...
Gil
 

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Discussion Starter #8
well I figured out some of my brass is regular and some is military. The non military is the same spec as the brass i was using so no worries. Thanks for the help.
 
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