Mike,
I am going to bet that he did it like I had mine done. Bore out the barrel to about 0.6" or so, then insert a turned and crowned barrel of your choice (mine is 17" of Lilja) and glue or solder in place. Just a short liner on steroids. Shoots ridiculously well.


_________
BrentD, (Professor - just for Stan)
=>/

[Linked Image from i.imgur.com]