Re: RCBS X DIES
My wife got me 3 sets of X dies a couple of years back for Christmas. I had not used them until about a month ago.
I'd been using Pacific dies for my Rem. 700 (.223) and Mini14 with no issues. My brother bought a set of Lee dies for his Savage varmint rifle (also .223) and had no issues with the reloads.
I'd been using his Lee Dies and my Pacific dies to reload for my AR15 (20" flat top) and my son's AR15 (also a 20" flat top) and the reloads have worked fine.
I just finished a 16" AR15 build and found out my reloads (with the Pacific and Lee dies)will only chamber in the new rifle about 6 times out of 10.
I got out the RCBS X die set, the Lee die set and the Pacific die set. I lubed the pad, put 30 .223 empties on it and with the Lee die 10 empties resized/deprimed just fine - only about 5 or 6 would chamber in the new rifle. I changed to the Pacific .223 resizing die and resized/deprimed 10 more cases. This time they were so hard to resize I thought I was gonna break the corner off my bench, man they were tough to resize. Again, only about 6 or 7 of the cases would chamber in the new rifle. I put the X die in the press and resized the last 10 cases. They were as easy to resize as the 10 with the Lee dies were and every one of them chambered easily in the new rifle.
They are not "small base" X dies but they are different enough that they will produce cases "better" for the new rifle than either my tried/true Pacific dies or the newer Lee dies.
YMMV but all my .223 brass is going through the RCBS X-dies from here out.