I've been using them for 223/5.56 but am wondering if I'm really benefitting.

I say this because I typically only get an average of 4-5 reloads out of once fired brass before I end up chucking that particular lot of brass.

If I trimmed .15 off ( as I typically do) and just used  a regular sizer die, would I really need to trim again after 4-5 reloads?

Thanks.

I have an X die in .223... but only because I was using a Possum Hollow Cutter chucked in a corded drill which was clamped in a vise to trim brass.

It was tedius and boring and loud.

Keeping the shorter trimmed brass from all my other brass is kind of a pain.

I have a Dillon toolheaded mounted trimmer on order.  It should be here any day.  It is going to go on my casefeeder equipped 650.

So from then on out I will just treat all my brass the same...It all gets dumped  into the casefeeder hopper and run through the resizing/trimming toolhead  and then through a second powder charging/bullet seating/crimping toolhead.

Follow the instructions and the X-dies work well. I've been using them in .220 Swift and .30-06 for a long time.

I use them (.223, .308 and .30-06).

I can't say they make the brass last longer as I don't really track number of loadings.

I shoot the .223's more than the other two.  At some point the shoulders crack (usually shoulder, sometimes the neck).  So far, not a single separation back near the base, as if the case was stretching.

My wife got the dies for me for Christmas one year.  I didn't start using them till I had an issue with a new AR15 build.  Had failure to chamber issues.  I had been using Lee dies for a few years with no issues, built a new carbine and had almost a 5 out of 10 failure to chamber rate.  Dug out my old Pacific .223 dies and got a slight improvement of 7 or 8 of 10 that would chamber.  Grabbed the RCBS X dies off the shelf and got a 10 out of 10 to chamber rate.  Put the Lee and Pacific dies away, pulled out the .308 and .30-06 X dies and have been using them ever since.

Even with my x dies, I used to get some that wouldn't chamber. This was before I was checking them with my Hornady Case Gauge.

The ones that wouldn't fit in the case gauge would get resized until they fit.

After that, all my loads chamber fine.

I have them for .308, I prefer regular dies/trimming cases.

Why?