.223 case trimming issues

jpslik · March 8, 2012, 03:39 AM

I've collected several once fired brass from a local range, all of various manufacturers. The shortest of these cases has been 1.730 and have not found 1 case longer then the recommended case length, but the manuels I've seen show that the cases should be trimmed to 1.760. What issues will I likely run into by trimming all my cases to 1.730. Also, when going for accuracy, is being +- .002 long or short on C.O.A.L. significant. Any help would be much appreciated

chris in va · March 8, 2012, 03:48 AM

Trim to 1.75, leave the others alone.

NWPilgrim · March 8, 2012, 04:55 AM

The issue you will find is a shorter case! That is, when you seat a bullet to the same depth (same place on the bullet body) you will have up to .030" less neck to hold the bullet and that much less case body for powder.

This could have no impact for what you are reloading. Some instances it could matter:

- Loads with bulky powder like Varget need all the case capacity they can get, it is usually a heavily compressed load. A shorter case may reduce the max powder charge you can compress into the case.

- A shorter neck (and 1.730" will be quite noticeably shorter) may not allow you to seat shorter bullets out as far to get better accuracy.

BTW, the cases often lengthen after you full length resize. So if you have not resized yet, be sure to measure their lengths AFTER sizing and then trim.

I trim to 1.750" and anything below that gets loaded as-is, and will eventually lengthen to need trimming.

603Country · March 8, 2012, 11:34 AM

The only problem, if it is a problem, is that the cases won't all be the same length. But, if you wanted to trim them all to the short length, I doubt it would matter. I say that because when I was a newbie reloader I accidentally power trimmed all of my 220 Swift brass to a considerably shorter length than recommended. I had just set the trimmer up wrong and started trimming. My Ruger 77V continued to shoot great groups.

**Unclenick** · March 8, 2012, 12:02 PM

NW Pilgrim hit it, I think. If you haven't resized them yet, the measurement is meaningless. After resizing them if they are still short, then they have either been trimmed more than usual by a previous reloader or they are a brand that is normally short. You occasionally run into that with specialty bullets, though I don't recall seeing it in .223, specifically.

The short cases won't likely give you a problem with long, heavy bullets. It used to be a standard service rifle match shooter's trick to cut cases for long match bullets down an extra .015"-0.020" below SAAMI minimum just so you didn't have to trim them again before you retired them. That's usually within five loadings for the M14/M1A using military brass. The same could be done with the .223 if you have a fast enough twist for the longer bullets.

The SAAMI spec for .223 cases is 1.740"—1.760". The standard trim length is simply in the middle of that range.

jpslik · March 8, 2012, 09:03 PM

Great info Guys, thanks. I'm using the 55 gr V-Max, which seems to seat well. I also wait to measure until after re-sizing each case. I'm trying to be very meticulous about every measurement.

March 8, 2012, 03:39 AM	#1
jpslik Junior Member Join Date: February 29, 2012 Posts: 2	.223 case trimming issues I've collected several once fired brass from a local range, all of various manufacturers. The shortest of these cases has been 1.730 and have not found 1 case longer then the recommended case length, but the manuels I've seen show that the cases should be trimmed to 1.760. What issues will I likely run into by trimming all my cases to 1.730. Also, when going for accuracy, is being +- .002 long or short on C.O.A.L. significant. Any help would be much appreciated

March 8, 2012, 04:55 AM	#3
NWPilgrim Senior Member Join Date: September 29, 2008 Location: Oregon Posts: 2,346	The issue you will find is a shorter case! That is, when you seat a bullet to the same depth (same place on the bullet body) you will have up to .030" less neck to hold the bullet and that much less case body for powder. This could have no impact for what you are reloading. Some instances it could matter: - Loads with bulky powder like Varget need all the case capacity they can get, it is usually a heavily compressed load. A shorter case may reduce the max powder charge you can compress into the case. - A shorter neck (and 1.730" will be quite noticeably shorter) may not allow you to seat shorter bullets out as far to get better accuracy. BTW, the cases often lengthen after you full length resize. So if you have not resized yet, be sure to measure their lengths AFTER sizing and then trim. I trim to 1.750" and anything below that gets loaded as-is, and will eventually lengthen to need trimming. __________________ "The ultimate authority ... resides in the people alone. ... The advantage of being armed, which the Americans possess over the people of almost every other nation ... forms a barrier against the enterprises of ambition." - James Madison

March 8, 2012, 12:02 PM	#5
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	NW Pilgrim hit it, I think. If you haven't resized them yet, the measurement is meaningless. After resizing them if they are still short, then they have either been trimmed more than usual by a previous reloader or they are a brand that is normally short. You occasionally run into that with specialty bullets, though I don't recall seeing it in .223, specifically. The short cases won't likely give you a problem with long, heavy bullets. It used to be a standard service rifle match shooter's trick to cut cases for long match bullets down an extra .015"-0.020" below SAAMI minimum just so you didn't have to trim them again before you retired them. That's usually within five loadings for the M14/M1A using military brass. The same could be done with the .223 if you have a fast enough twist for the longer bullets. The SAAMI spec for .223 cases is 1.740"—1.760". The standard trim length is simply in the middle of that range. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

March 8, 2012, 03:48 AM	#2
chris in va Senior Member Join Date: December 26, 2004 Location: Louisville KY Posts: 13,806	Trim to 1.75, leave the others alone.

March 8, 2012, 11:34 AM	#4
603Country Senior Member Join Date: January 6, 2011 Location: Thornton, Texas Posts: 3,998	The only problem, if it is a problem, is that the cases won't all be the same length. But, if you wanted to trim them all to the short length, I doubt it would matter. I say that because when I was a newbie reloader I accidentally power trimmed all of my 220 Swift brass to a considerably shorter length than recommended. I had just set the trimmer up wrong and started trimming. My Ruger 77V continued to shoot great groups.

March 8, 2012, 09:03 PM	#6
jpslik Junior Member Join Date: February 29, 2012 Posts: 2	Great info Guys, thanks. I'm using the 55 gr V-Max, which seems to seat well. I also wait to measure until after re-sizing each case. I'm trying to be very meticulous about every measurement.