Cliff notes ....

Hornady cuts a die with a nominal caliber neck that is deep enough to hold 5-6 threads for the mags and shallow enough to touch the shoulder but not the shell holder of the shorter cases . The 6.5 will reach the Grendel and 264 , the 270 does the 6.8 out to at least 270 Win . I had hoped the 6.5 was a bushing type ..... They do have multiple expander balls .

I got a 6.5 cheap enough but the expanders didn't go big enough or small enough for a 6.5 Japanese I have that needs a .272/3 cast/paper patch and the 270 should get it without an expander . This particular one in a standard die moves the neck almost .1 every cycle .