When I was a cop in the Denver metro area during the late 90s, I had a Mini-14 (Hmmm, may have a trend...) that I had as a Patrol Rifle. I couldn't yet afford a Colt or Bushmaster like the cool kids on the Department.
When I could, I got a new Colt AR-15 with the A3 Upper and a full rifle stock. I was happy. That is, until I had to qualify with it. That thing made my now-departed Mini-14 seem like a National Match Garand.
I guess I got either a Monday gun or a Friday gun. Just put it this way, I had more faith with my with Vang-tuned, personally-owned, Department approved Remington 870P loaded with Federal Hi-Shok slugs at 75 yards than I did with my rifle. That's why the 870 and I were constant patrol partners.
Fast forward to 2008. I had a decent Wilson UT-15. I put some $$$ into its build and never really had much faith in it either. I spent close to 50 rounds and almost 1-hour devoted to just getting it to print on paper. No dice.
So, I got in my SAAB (yeah, one of those Swedish Fish conveyances...) and drove to my LGS (in Newport, NC) and traded the owner straight across for a new Colt AR-15 (6520) with the light barrel and A2 upper. That one redeemed my esteem for Colt. It must've been a Wednesday gun. It would shoot anything (45, 55, 62, 72, 75, 77 grain bullets) into a tight group under an inch.
Ruger Mini-14, Colt AR-15A3 (L.E. Carbine during the Clinton years) and sadly the $2300 UT-15 are my Waterloos.