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Old August 25, 2011, 02:12 PM   #1
DarthNul
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chamfer & deburr pistol cases?

I have two projects that require trimming pistol brass: Uniforming the length of a batch of .45ACP cases so they're all .890, and converting a couple hundred 9mm Luger cases to 9mm Makarov (My new F.E.G. PA-63 should be in tomorrow).

I can see some value in taking the edge off the outside of a case mouth after trimming, even if it's just to avoid small cuts to fingers, but since the cases will all be belled before bullet seating, is chamfering really necessary? I'm thinking that flaring the case mouth will be enough to prevent any material getting scraped off the bullet.

Agree or disagree?
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Old August 25, 2011, 02:26 PM   #2
Sensai
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Disagree, burrs on the inside cause scratches on the bullet. If they're pushed inside the case they can cause uneven bullet tension. Why not just hit the neck one time with the chamfer tool? It doesn't hurt much, I promise.
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Old August 25, 2011, 02:34 PM   #3
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I've had a number of cases where, after cutting but not chamfering, I found a small ring of brass (the wire edge) sitting at the case mouth. It think it popped off when the bell was ironed out. Those should just blow out with the bullet, and probably would most of the time, but I pulled them off over the bullet with a dental pick so it couldn't snap off and fall into the magazines or into the gun. So, I think for brass you will bell with an expander, its removing that wire edge that you chamfer for. If you don't chamfer, the expander may just raise the edge upward, in which case it will be sharp enough to shave lead as the crimp closes in. A light chamfer will clear it just fine. Also, you only have to do this once. You don't normally have to trim pistol brass at all as it either stays about the same or shrinks with reloading. Just keep the stuff together by the number of reloads and it should shrink about the same.

FYI, 0.892" is SAAMI minimum for .45 ACP. I've shot it a lot shorter than than with light target loads, as I've had some shrink as short as 0.873". But with full power crimped loads you wouldn't want to get it quite that short without double-checking that your pressure wasn't increasing (velocity increase would be a strong clue in this instance).
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Old August 25, 2011, 03:26 PM   #4
DarthNul
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Quote:
FYI, 0.892" is SAAMI minimum for .45 ACP.
Hmmm... A good bit of the once-fired brass I have is shorter than that, and the "trim to" length spec I see most often is .888.

I wonder how much $ the manufacturers save by skimping on a couple of thousandths of an inch.
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Old August 25, 2011, 04:08 PM   #5
Unclenick
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Correction

I was remembering wrong. I thought the spec was 0.898-0.006", but I checked and it is 0.898-0.010", so 0.888" would be minimum and and 0.893" would be the trim-to length, as those are always set right in the middle to allow maximum ± trim error by the manufacturers. Cases more commonly have a -0.020" tolerance, but not the shorties. So, I can see how the trim-to might be assumed to be 0.888" if the writer didn't look it up, just as I failed to in my last post.

My target loads always shortened about 1/2 a thousandth per load cycle, so they always got low after awhile. Run 40 to 50 reloading cycles on good, tough brass, and shorties are what you get.

Maybe if I shot it long enough I could sell it to someone with a .45 GAP? At about 50 reloads the headstamps were getting kind of indistinct anyway.
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Last edited by Unclenick; August 25, 2011 at 04:25 PM.
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Old August 25, 2011, 06:58 PM   #6
Sidewinder72
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Chamfer and debur pistol cases. Absolutely, how else are you going to make an accurate load when everything is not the same. Just me
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Old August 25, 2011, 07:52 PM   #7
243winxb
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Always chamfer & deburr after trimming.
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Old August 25, 2011, 08:46 PM   #8
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I always chamfer & deburr new cases and once fired as well as after trimming.
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