I recently purchased a second hand race gun. It's basically a modified Colt 1911, with mount holes drilled for the red dot scope; a trigger job, and a suppressed match barrel. The gun shoots accurately, but has crap reliability. The red dot scope will not hold it's zero. I am unwilling to spend a ton of money one a new red dot scope, so I purchased some adjustable rear sights. Now the sights won't fit, because the screw hole doesn't line up. This gun is turning out to be a lemon, and my basic gunsmithing skills are proving inadequate.