I had the same need. Wanted to try and cure my clickers, found out RCBS used to make a small base die, but they discontinued it. Somebody suggested the Redding shoulder bump die, got one, but it sized the base of the case even less than the Hornady “custom grade” FL die (NOT a custom die).
Sent the Redding die off to Porter Precision Products in Lake Jackson Tx, and Kenny Porter converted it into a small base die that reduces the case diameter at the 0.200” line by another 1.5 thou (in addition to the sizing done by the Hornady FL die).
The neck and shoulder area was bored out, so it does not touch the shoulder or the neck, and the die was shortened to increase the amount of sizing, so only the case taper was retained. I now get the web area reduced (in total) by just under 3 thou in total, in two sizing steps.
Will see if that cures the clickers. It is 16x fired ADG brass in a tight chamber, and the brass is getting close to end of life. Not ADG’s fault that i get clickers in a tight chamber with fairly stiff loads.
Btw: A slightly larger chamber would be the best permanent solution.