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RERICK
July 22, 2006, 08:13 PM
I measured my chamber so I could trim brass for a more custom fit,The measurement was 1.783.That to me seem too deep considering most load books call for trimming to 1.750 and the max to be 1.760 for a .223.

cntryboy1289
July 22, 2006, 09:28 PM
Do a chamber cast of it using cerosafe and mic it. A .223 doesn't usually have to many problems with headspace, but yours could have been chambered to deep to begin with. How did you measure the chamber to begin with?

When you reload, you fireform the brass to make the brass fit your chamber better and then necksize it to keep it where it is. I trim when the brass gets too long to chamber correctly. I would urge you to take a look at the SAMMI specs before you do anything with it other than a chamber cast.

DnPRK
July 22, 2006, 09:33 PM
How were you measuring the depth?

Are you measuring the depth to the end of the neck cut? or neck + freebore?

RERICK
July 23, 2006, 06:41 PM
I did it with a case gage tool.Then I measured it with a caliper

Ammo Junky
July 23, 2006, 07:06 PM
The chamber length usualy is .015 to.030 longer than sammi max for case over all length. It is a big issue for safe pressures. You can let your case grow within .010 of your chamber oal, but it is safer and simper to just stay .010 to .020" below sammi max. Theoreticly could be more accurate with a longer neck for better support, but not worth the trouble for me.

Unclenick
July 23, 2006, 07:43 PM
Ammo Junky has it right. They want to be sure a maximum trimmed case can't grow far enough to reach the chamber's neck cut in a single shot. That usually isn't more than 0.005" growth, but someone with a really hot load and a tight bullet fit could do it. Clymer specs their .223 reamer at 1.7720" to the case neck shoulder from the base if the chamber is dead minimum tight. Your's is a little loose compared with that, but you have to subtract how far your headspace is above minimum to get a comparable number.

Nick

RERICK
July 23, 2006, 08:17 PM
So if mine is at 1.783 and the standard max is 1.760 thats .23 above the max?Like I said that seemed too much.I have heard for accuracy to trim to
.10 below the the chamber length.So if thats true I should trim to 1.770?
Am I missing somthing?:confused:

Ausserordeutlich
July 24, 2006, 11:21 PM
Yeah, I believe you're confusing trim length with loading a few thousandths off the lands, which has nothing to do with trim length. Trim length, relative to your rifle's chamber dimensions probably isn't anything worthy of further thought on your part.

RERICK
July 25, 2006, 10:53 AM
No I am referring to the trim length of the brass not the seating depth.

tINY
July 25, 2006, 11:57 AM
You don't ever want the brass as long as the chamber. That can cause the brass to crimp the bullet and dramatically increase chamber pressures.

Unless you want to blow the bottom plate off your magazine, just trim the cases and be happy that you have a little extra length in case you get sloppy.



-tINY

Unclenick
July 25, 2006, 02:47 PM
Rerrick,

If you take the Clymer Reamer as a "normal" chamber profile, then your length, 1.783", minus Clymer's, 1.772", means your chamber is 0.011" over the Clymer spec. Not a big deal in my opinion. The length of your neck has some effect on how well the bullet is kept supported and aligned with the bore, but 11 mils won't matter to that. This extra space is, as I said before, just there to make sure your case mouth never stretches far enough to reach the part of the chamber where the neck steps down to the freebore. If it did, as tINY said, you would get high pressure because the pinching of the case mouth that results prevents the neck from letting go of the bullet properly.

Nick

RERICK
July 25, 2006, 07:00 PM
Thanks Nick.Thats the answer I was after.I always check the length of my brass before I load and what I was told was to trim to within 0.010 for good bullet support and thats all I am trying to do.I was just a little concerned that the chamber was cut too deep was all.