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rick t

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I don't think so.

Go here:


At that video screen you will see a little "tab" option for the RCBS X sizer die (caliber specific) video.

Click on that, and watch the video.

In the video, they show a cut-away X die and how it works.

There is NOT a seperate bushing like what you could get for neck only sizing die.

Versus conventional el cheapo rifle die sets, it appears to me that the X sizer die is not forcing the case's mouth back over some expander ball (on the ram's down stroke), which is where I think the typical brass growing/stretching problem occurs.

Here is the instruction manual for the X die:


IIRC, you have an option for the first step w/ once fired brass:

A. resize your bottle necked rifle brass with a normal expander ball type of resizing/decapping die


B. resize with the X die, but with the mandrel in the UP position

Then you trim to 20 thousandths under the trim to length (I think) as specified in whatever reloading manuals you are referencing. So, IIRC, for .223 brass the trim to length is supposed to be 1.75, I think. So trim to 1.73" .

then you load it up and shoot it. When you get that brass back, then you can treat the brass like straight walled pistol brass with just one trip through and one toolhead on a 550, 650 or 1050 when you screw the X die's mandrel DOWN .

Edited by Chills1994
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I use the X die in .223 without the initial undersized trim recommend by RCBS.

It works great. I have never had to trim a case throughout the entire life of the case.

I know bench rest shooters freak out if the necks get a little thicker but it does not matter a bit for action shooting.

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I know bench rest shooters freak out if the necks get a little thicker but it does not matter a bit for action shooting.

I was in a discussion on this with some guys, RCBS advertises the die does NOT thicken necks. In the discussion it was clear we all were guessing so I started with new brass, measured neck thickness and proceeded to fire,reload,fire,reload....I don't remember the exact number of times fired or reloaded but I do remember the neck changed very, very little

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Back when I was thinking about buying an X die, I called up RCBS and got a hold of their technical people. I told the guy, "This'll be for an AR." He replied back, "Okay, then you will want the small base X die."

I think the general consensus here on the forums is that if you are getting once fired .223 brass from some other source...like military brass or police brass... stuff that could have been shot out of all kinds of wollered out chambers, then go with the small base die.

If... I think... you get your own .223 brass back and use that exclusively, then you could probably get by with the regular X sizer die. Even moreso if it is strictly going back into a bolt action gun.

The small base die is supposed to help with reliability in semi-autos.

It was either on this forum or maybe a guy I was PM'ing back and forth on YouTube, but he said if you could avoid it, stay away from brass that has been shot out of a machine gun... as to the provenance or pedigree of military brass and whether it has been through an M249 SAW... I couldn't tell ya. I think he went on to say that the machine gun brass has a shortened life expectancy and what he thought was more likely to suffer from a case head separation...sooner.

Edited by Chills1994
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