How short should I trim my rifle cases?

Luciano · April 10, 2007, 10:49 PM

I'm loading 25-06 Rem wich has a max case length of 2.494 I noticed that some of the new Win cases I bought are pretty short so I trimmed them to 2.478.Is that a bit short and why?Thanks

hivel37 · April 10, 2007, 11:34 PM

Most manuals give a "trim to" measurement. I usually trim to about .006 below maximum. As I understand it, if cases trimmed much below minimum are used, chamber erosion can occur. How many such rounds it would take to cause this, I don't know.

hivel37 · April 10, 2007, 11:40 PM

By the way, if they were already short, why did you trim?

**Unclenick** · April 10, 2007, 11:43 PM

I usually trim 0.015" below maximum. This is because randomly sampled cases from new bulk brass can be as much as 0.012" under maximum to begin with. By going to 0.015" under maximum, I am sure to have trimmed them all the same length. I will not have to trim again for at least 3 reloads, letting the necks gradually grow back toward maximum.

Nick

WCW · April 11, 2007, 11:25 AM

I maintain all rifle cases to .006 below maximum length. If I start a new batch of cases I just continue loading them until they require trimming. I have never noticed any appreciable difference in accuracy with slightly shorter cases in my 25-06 Remington Sendero.

Luciano · April 11, 2007, 02:19 PM

I trimmed them because I wanted an uniform case length.As Unclenick mentioned some new cases are .012 under the the max.Perhaps I'll let them "grow" a bit.

brselman · April 11, 2007, 02:53 PM

Unless I am mistaken and have read the rcbs fl x-sizer die instructions incorrectly, rcbs recommends an initial trim to 0.020" off of the maximum. They claim when using their x die, you should never have to retrim thereafter. Anyone have any experience?

Ifishsum · April 11, 2007, 03:42 PM

I've had several batches of new Win brass that I had to trim a bit short just to get the necks square. No ill effects that I can see, and I don't have to re-trim as often.

Most loading manuals give a trim-to length of .010 under maximum.

brickeyee · April 11, 2007, 07:42 PM

You can always measure the chamber and then determine what the correct length is for that gun.
A chamber cast will reveal all sorts of things.
You can also do it with special plugs.

mrawesome22 · April 11, 2007, 07:57 PM

Use the data in your books.

April 10, 2007, 10:49 PM	#1
Luciano Senior Member Join Date: March 22, 2006 Posts: 111	How short should I trim my rifle cases? I'm loading 25-06 Rem wich has a max case length of 2.494 I noticed that some of the new Win cases I bought are pretty short so I trimmed them to 2.478.Is that a bit short and why?Thanks

April 10, 2007, 11:43 PM	#4
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,060	I usually trim 0.015" below maximum. This is because randomly sampled cases from new bulk brass can be as much as 0.012" under maximum to begin with. By going to 0.015" under maximum, I am sure to have trimmed them all the same length. I will not have to trim again for at least 3 reloads, letting the necks gradually grow back toward maximum. Nick __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

April 11, 2007, 02:53 PM	#7
brselman Member Join Date: February 13, 2006 Location: Johnson City, TN Posts: 78	Trim length Unless I am mistaken and have read the rcbs fl x-sizer die instructions incorrectly, rcbs recommends an initial trim to 0.020" off of the maximum. They claim when using their x die, you should never have to retrim thereafter. Anyone have any experience?

April 10, 2007, 11:34 PM	#2
hivel37 Senior Member Join Date: August 24, 2004 Location: Hill Country Posts: 522	Most manuals give a "trim to" measurement. I usually trim to about .006 below maximum. As I understand it, if cases trimmed much below minimum are used, chamber erosion can occur. How many such rounds it would take to cause this, I don't know.

April 10, 2007, 11:40 PM	#3
hivel37 Senior Member Join Date: August 24, 2004 Location: Hill Country Posts: 522	By the way, if they were already short, why did you trim?

April 11, 2007, 11:25 AM	#5
WCW Senior Member Join Date: March 6, 2007 Posts: 132	I maintain all rifle cases to .006 below maximum length. If I start a new batch of cases I just continue loading them until they require trimming. I have never noticed any appreciable difference in accuracy with slightly shorter cases in my 25-06 Remington Sendero.

April 11, 2007, 02:19 PM	#6
Luciano Senior Member Join Date: March 22, 2006 Posts: 111	I trimmed them because I wanted an uniform case length.As Unclenick mentioned some new cases are .012 under the the max.Perhaps I'll let them "grow" a bit.

April 11, 2007, 03:42 PM	#8
Ifishsum Senior Member Join Date: September 15, 2005 Location: Oregon Posts: 1,033	I've had several batches of new Win brass that I had to trim a bit short just to get the necks square. No ill effects that I can see, and I don't have to re-trim as often. Most loading manuals give a trim-to length of .010 under maximum.

April 11, 2007, 07:42 PM	#9
brickeyee Senior Member Join Date: December 29, 2004 Posts: 3,351	You can always measure the chamber and then determine what the correct length is for that gun. A chamber cast will reveal all sorts of things. You can also do it with special plugs.

April 11, 2007, 07:57 PM	#10
mrawesome22 Senior Member Join Date: November 9, 2005 Location: Ohio, Appalachia's foothills. Posts: 3,779	Use the data in your books.