...I'm using the .115 front that came with the set...I was initially a lil' CONFUSED after I put 'em on my 17, 'cause the "Sight Picture" looked just a lil' TIGHTER than I remember it being on a friend's 17...what he told me was that, originally, Dave S. spec'ed the front to be .110...and, being an EARLY set, that is what my friend's mikes out at...in later production runs, whatever vendor WTS/Sevigny are using deviated slightly from "Spec", and the fronts have been .115 since then...anyway, I think that they are a HUGE improvement over the "Plastic" sights that came on the gun...I MAY try a SLIGHTLY narrower front at some point, just for giggles 'n' grins....FWIW....mikey357