Rcbs X-die 223 trim length

Currently loading for the AR platform, looking for decent, reliable ammo, not chasing the last thousandth on target.

How important is the initial trim length with the rcbs x die?
Will 1.750” work instead of 1.740”?

I use a Lyman E-zee case trimmer, so length is fixed at 1.750”.
RCBS instructions say to initially trim to -.020” under max.
SAMMI 223 remington cartridge specs Show 1.760-0.030”

https://saami.org/wp-content/uploads...sting-Copy.pdf
P.68

So do I need a new adjustable trimmer (or modify the Lyman pilot).
Or will 1.750” work with the RCBS X-die?

I’m setting up to reload .223 much more than I have and finally buy the X-die, currently using standard RCBS 2 piece die set.

I think I have settled on the standard instead of the Small Base (SB) also.
If I was reloading for others I might use the SB, but I don’t let others shoot my reloads.
And if I ever get a problem rifle then I will fix it’s chamber instead of all my brass.


Matt


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I've loaded a lot of 223/5.56 using the RCBS standard X-die to size the cases. I don't bother to trim the cases, even the first time as per Lee's instructions. Using a Headspace/trim length gauge, case oal measurement and chamber casts I've found it is not necessary when using new or once fired (out of bolt guns, SSs, M16/ARs, etc. not MGs) LC or other milsurp cases. A cleaned, lubed new or once fired case is run into the die with the shell hold bumping solidly against the bottom of the die (no cam over) then the mandrel is tightened down against to case mouth. With that, if the sized case gauges within spec, the X-die is then adjusted. Have not trimmed a 223/5.56 case since I got the X-de. I shoot them in my ARs and Contender carbine which need the FL sized case w/o problems. For my bolt guns I usually NS with cases relegated to the specific bolt gun. However, for PD shoots with 3 different 223s I FL size with the X-die for a "one size fits all" lot of ammo.

The SB or "AR" x-dies are not needed for standard 223/5.56 chambers. If one has a minimum spec match chamber then maybe so. If not then the standard X-die sizer with work best w/o over sizing the cases.

Thank you Larry.
I was hoping you would see this.
Sounds even better if no trimming is needed, one less step.


Matt


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How does the x-die work?

When fired, a case expands in diameter and in length from shoulder to base. Normally full length sizing adds a little more to length then bumps the shoulder back so the excess ends up in the neck and the expander ball then also tends to stretch the neck. With all the excess brass pushed forward it is then trimmed off.

That’s a lot of stuff to avoid with one die. I’m excited to try it, but before I spend the money can someone explain it? If it doesn’t FL size or bump the shoulder back how many firings do you get before the round won’t chamber? How is this different from just neck sizing?

Someone else can explain it better, but my understanding is that there is a mandrel in the die that contacts the case mouth and limits case length growth.

https://www.rcbs.com/on/demandware.s...structions.pdf

Larry Gibson has some other posts on here that describe its operation and use, not sure how long ago they were, maybe in the last year or two.

His reviews sold me on the die, I just wasn’t loading enough rifle to get one, and then this summer they were hard to find.


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The X-die has a case length limiter in the neck, i.e., a smaller diameter that hits the case mouth and collapses the neck into the shoulder. It does not because it can not cause the neck to spread back into the shoulder, it simply puts the extra neck inside the case. All that's a fact.

My opinion is that RCBS says to shorten the neck so much before use that any case that's impacted by the die has already stretched as much as is safe and therefore the case should probably be tossed.

I have an X die for 6.5x55. It’s convenient but I’m wondering if it will make any difference in case life. Since I moved from New Mexico to the greater Houston area I anticipate that I will shoot less.

I have a standard 223 X die. It works as advertised. I would try the 1.75" trim length, and see how it goes. Most likely fine.

I have buckled a few cases that sneaked into the reloading assortment that had not been initially trimmed. So my experience is slightly different than Larry's in that regard.

I've used the SB 223 x-die with trimmed brass and annealed untrimmed brass. I prefer the annealed brass. My process is tumble brass to clean, anneal the necks, and then full length resize without cam over. I tumbled the brass again to remove case lube.

Every piece of brass passed a case cage, none had collapsed necks or bulged shoulders. The brass without trimming was once fired to many fired. I believe neck annealing made the difference. I used a propane torch and battery drill with a socket to turn case. Annealing took a normal 6-count for 6-7 seconds in the flame. 200 cases took about 25 minutes. Resizing after annealing was worth the time spent annealing. No cracked necks, no neck separation, no hard to resize cases.

Careful case neck annealing (done right) is helpful. But, IF we anneal necks to any visible red glow we will have destroyed the "springy-ness" of the metal and the necks will have a very low ability to grip bullets.

(I use over annealed cases for cast stuff, the light grip won't squeeze oversize bullets down.)