Welcome to tfl!
First, what brand of dies are you using?
IF the decapping stem is too large to enter the mouth of the fired case, it is the wrong one. Contact the die maker, for the right one.
I don't load for the K-Hornet, but I do for the regular Hornet, and it's a chore. Cases are almost paper thin at the mouth, and I've crushed more than a couple. One thing that helps is a very "generous" chamfer on the case mouth, and working slowly and carefully seating the bullets.
Get ahold of who ever made your dies and tell them what's going on, they should send you the right stuff, usually at no charge.
A "work around" is the Lee decapping set, a punch and base set with two different size punches, the smaller one does .22 cal the larger .30
This does not, however replace the expander "ball" on your die decapping stem. You need the right one.
(also, check your computer, auto-correct might be turning "collet" into "collect" mine turns "spitzer" into "spritzer" when I'm not looking...
)