The gas check check shank on my Lee 310 grain boolits is too wide to accommodate my Hornady gas checks. I tried several things unsuccessfully, and finally found this in my junk box. It fits the bill perfectly... a couple of taps and the gas check expands perfectly.
I thought I would post this in case somebody whose looking for one more idea happens to come across it. Unfortunately I don’t know where I got this particular nylon insert nut, and am being careful not to toss it back into the junk box.
Randy