Sorry dont have experience with either version Unertl (modified vs unmodified) but truth be told if there was a history of at least one M40A1 mounted with the S&B 3-12X50 PMII I wouldnt be in the scope hunt right now......well I might be because the Unertl/MST100 just looks cool (and right) on that gun.
My Weaver 10X is working out real well for me and things will only get better with the MST 100 being able to dial for daily conditions rather than screwing with capped turrets. Im finding 10X is plenty of mag to make a bullet hit something but if looking to make groups, more mag would be better.