i have a 617 that i bought about a year ago and a 17-4 that i bought about 4-5 month ago. i couldn't believe the difference that not having an underlug made. both have the target grips but holding them up together there is no doubt that the 17 feels better to me. if you are considering useing the 617 as practice for a 686 then maybe consider a 17 and get a mod 19 to match. Doeboy