I agree with those who've said to find out which 40s the Toledo PD and adjacent agencies accept for duty use. Odds are they will be polymer so you might have to reconsider that point. Myself, I prefer the Glock 23 especially a Gen 4 which has different backstraps to fit more hand sizes. The Glock 22 is slightly larger and the Glock 27 is smaller. All three are .40S&W.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together. You'll remember the quality of a gun long after you forget how much you paid for it.
US Army 1966-69, VFW Life Member, Retired Geek