Originally Posted by HotGuns

Just a note about the various .22 caliber conversions out there.

Some are good and some are not so great. If you buy a conversion kit, you will only achieve mediocre accuracy from the .223 barrel because the twist is not fast enough for the shorter,slower .22 bullet.

For the best accuracy on the AR platform, you must buy a dedicated .22 AR upper. This will consist of the whole top half, complete with bolt and the proper twist barrel for the .22 Long Rifle.

Most of the dedicated uppers will out shoot the drop-in-bolt conversions kits.
If you aren't too concerned about accuracy and 2-3 inches at 50 yards is good enough then the drop-in- bolt kits are fine just for plinking.

If you want some good accuracy, around 1/2" at 50 yards, then you need to get the whole top half.