@Paul in OKC
Yes, that works .... but .... surprisingly ( !!!! ) that results in a shorter pen !!!
You're referring to the old "Sierra Button Click" ( still for sale on Berea website, I think ).... and there is a new "Sierra Super Button Click" which does not have the extension piece - it uses the newer Schmidt SKM-88 click mechanism and has a different brass tube length .
In the older Sierra click pen the extension piece is metal and is almost exactly 0.5" long.
So you can shorten the brass tube by 0.5", ending up with a brass tube length of 2.42 - 0.5 = 1.92" (approx) ... kinda short, IMHO.