When to trim?

Nukem · March 12, 2000, 06:45 PM

I kind of toss this around in my head.
Should I trim my brass after resizing or before? I usually trim after resizing because of the effects of the expander ball and any shoulder setback on OAL. But, then I have noticed that the pilot of the trimmer may be altering the neck tension of the sized round due to the effort require to get it to enter?
Any thoughts?

Big Bunny · March 12, 2000, 08:39 PM

I trim when over length on caliper. If you would like to trim AFTER resizing, I suggest you get your pilots trimmed down a tad so that they do not alter the case neck by being forced in. But perhaps allow a few thou for ambient temperature changes and for the tool to heat up when operating.
I cannot see the advantage of trim AFTER re-size, as long as the case is clean and free from dents etc, but if the case is trimmed slightly UNDER the case recommended length before resize(there are some variations from manufacturer to manufacturer)this does not really matter, it is the over-sizes which can increase pressures or prevent functioning and a well lubricated case should not "pull" or elongate the case neck atall.

But check your own chamber, you could need a pet length for your ammo only. They do vary a lot, especially Mil types, and EG a telescoping gauge may show this, though I have never done this myself, and have trusted the published data with no problems yet.

But any comments or argument on this would only be appreciated...I am always interested in new ideas (or rehashes of old ones !)

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***Big Bunny***

Paul B. · March 13, 2000, 01:59 AM

Nukem. I've always trimmed after resizing. Some cartridges will lengthen somewhat during resizing. The 7x57 can be a prime offender in this realm. For example. according to one source, the maximum length is 2.235" for the 7x57 case. The trim to length is 2.225" If I full length resize, I have to trim after the second reloading. There is almost no stretch on firing, but most occurs during full length sizing. I can go about four reloads before trimming, if I just neck size.
Paul B.

[This message has been edited by Paul B. (edited March 13, 2000).]

bradleyt · March 14, 2000, 01:23 PM

All of my 2 and 3 die sets use die #1 to accomplish several things: punch out the old primer, resize the case, and expand the case mouth. Dragging the expander ball through the case mouth is a large cause of overlength cases. That is why you can buy lube for the the case mouth.
This is also why most of the people I know trim after resizing. If you are having trouble getting the pilot in the case you are either using the wrong pilot, it is the wrong size, or your expander ball is the wrong size. I had to send my .243 resize die back for that very reason.

Big Bunny · March 14, 2000, 09:06 PM

I meant mainly neck-sizing for bottle-necked rifle cartrdges in my last posting.
I can quite see FLS there could possibly increase length, depending on the volume of brass which needs to be "flowed" . But it must come from somewhere and case-separation may well be the next surprise !

But I can't say I have had any problems myself with milder than factory loads and up to and over 7 reloads possible from my .222 Rem 788 without resizing, though I have had to outside neck-ream on some cases, due to uneven thickness of the brass and consequent bullet mis-alighnment on subsequent reloading.

A combination FLS and trim tool is advertised for sale, I believe. Uses a file to remove surplus brass over the hardened die.Then you chamfer with a Lyman-type tool by hand, inside and out.

------------------
***Big Bunny***

Paul B. · March 14, 2000, 10:18 PM

Big Bunny. Years ago, I did about 850 30-06 cases with one of those file and trim dies. Never again. Talk about sore hands. Another thing. Even with a neck sizing die you have an expander button. There is where a lot of the stretch comes from.
Paul B.

March 12, 2000, 06:45 PM	#1
Nukem Senior Member Join Date: January 29, 2000 Posts: 709	I kind of toss this around in my head. Should I trim my brass after resizing or before? I usually trim after resizing because of the effects of the expander ball and any shoulder setback on OAL. But, then I have noticed that the pilot of the trimmer may be altering the neck tension of the sized round due to the effort require to get it to enter? Any thoughts?

March 12, 2000, 08:39 PM	#2
Big Bunny Senior Member Join Date: August 9, 1999 Location: New South Wales - Australia Posts: 605	I trim when over length on caliper. If you would like to trim AFTER resizing, I suggest you get your pilots trimmed down a tad so that they do not alter the case neck by being forced in. But perhaps allow a few thou for ambient temperature changes and for the tool to heat up when operating. I cannot see the advantage of trim AFTER re-size, as long as the case is clean and free from dents etc, but if the case is trimmed slightly UNDER the case recommended length before resize(there are some variations from manufacturer to manufacturer)this does not really matter, it is the over-sizes which can increase pressures or prevent functioning and a well lubricated case should not "pull" or elongate the case neck atall. But check your own chamber, you could need a pet length for your ammo only. They do vary a lot, especially Mil types, and EG a telescoping gauge may show this, though I have never done this myself, and have trusted the published data with no problems yet. But any comments or argument on this would only be appreciated...I am always interested in new ideas (or rehashes of old ones !) ------------------ *Big Bunny*

March 13, 2000, 01:59 AM	#3
Paul B. Senior Member Join Date: March 28, 1999 Location: Tucson, AZ Posts: 3,802	Nukem. I've always trimmed after resizing. Some cartridges will lengthen somewhat during resizing. The 7x57 can be a prime offender in this realm. For example. according to one source, the maximum length is 2.235" for the 7x57 case. The trim to length is 2.225" If I full length resize, I have to trim after the second reloading. There is almost no stretch on firing, but most occurs during full length sizing. I can go about four reloads before trimming, if I just neck size. Paul B. [This message has been edited by Paul B. (edited March 13, 2000).]

March 14, 2000, 01:23 PM	#4
bradleyt Member Join Date: April 2, 1999 Posts: 35	All of my 2 and 3 die sets use die #1 to accomplish several things: punch out the old primer, resize the case, and expand the case mouth. Dragging the expander ball through the case mouth is a large cause of overlength cases. That is why you can buy lube for the the case mouth. This is also why most of the people I know trim after resizing. If you are having trouble getting the pilot in the case you are either using the wrong pilot, it is the wrong size, or your expander ball is the wrong size. I had to send my .243 resize die back for that very reason.

March 14, 2000, 09:06 PM	#5
Big Bunny Senior Member Join Date: August 9, 1999 Location: New South Wales - Australia Posts: 605	I meant mainly neck-sizing for bottle-necked rifle cartrdges in my last posting. I can quite see FLS there could possibly increase length, depending on the volume of brass which needs to be "flowed" . But it must come from somewhere and case-separation may well be the next surprise ! But I can't say I have had any problems myself with milder than factory loads and up to and over 7 reloads possible from my .222 Rem 788 without resizing, though I have had to outside neck-ream on some cases, due to uneven thickness of the brass and consequent bullet mis-alighnment on subsequent reloading. A combination FLS and trim tool is advertised for sale, I believe. Uses a file to remove surplus brass over the hardened die.Then you chamfer with a Lyman-type tool by hand, inside and out. ------------------ *Big Bunny*

March 14, 2000, 10:18 PM	#6
Paul B. Senior Member Join Date: March 28, 1999 Location: Tucson, AZ Posts: 3,802	Big Bunny. Years ago, I did about 850 30-06 cases with one of those file and trim dies. Never again. Talk about sore hands. Another thing. Even with a neck sizing die you have an expander button. There is where a lot of the stretch comes from. Paul B.