As a retired machinist with 35 yrs experience I will say this, take it for whatever you feel its worth; The Walker system will generally give good results on those chokes "With a Parallel". You only take very light cuts & the reamer will generally follow the existing bore.
"If" on the other hand you try it on a taper choke (No Parallel) & it stays straight with no shift of impact rush straight out & buy "ONE" lottery ticket, anybody that luckey only needs one.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra