OK here is the latest on my saga. Before putting the replacement upper on my colt I had to get a small pin conversion. Now ready for the range. Had nothing but trouble with the complete upper I had purchased. At 25 yards could even hit a 2x4 target anywhere! So I moved the target to 10 yards and tried again. Was shooting way right, adjusted the windage, still shooting right, adjusted some more, still shooting right. Adjusted till there was no more adjusting and at 10 yards was 5 to 6 inches right! On top of that it was jamming every 3 to four rounds. This sucks! so Local gun store (Greyson Guns) agreed to replace the upper with a newer one no cost difference. Put everything together again and back to the range (actually in store). The upper could be sighted in but kept jamming. It wouldn't eject the brass and would jam. Twice had a round jam in the breach so bad that had to use a cleaning rod to tap out the stuck brass. So the upshot is that gun store will credit my account for the 2nd upper and I will put the original upper back on and shoot it and not abuse it.