I just read a GT review on some top-notch revolvers with 8 1/2 " barrels and only one could manage groups sub-inch groups at 25 yards from a rest. That said, I have on two occasions shot 1" groups (five rounds) with my 686 revolver and Ultra-dot scope.... so obviously luck AND skill are required for such feats.
Most VERY GOOD production 1911's in .45 (Kimber, Para Ord, STI) usually check in with typical groups around 1.5" (give or take a bit) depending on ammo. Groups significantly better than that probably had an assist from the good Lord or just good fortune.