I have a Palmetto Colt 9mm lower. Turned it into a great build, it is a nice lower and was a great price.
I have the non-lrbho glock lower too. Also very nice, work great, but I still wish Palmetto kept making the Colt pattern lowers too. Great lower. Bolt hold open always works, and functions perfectly with metalform mags. It is such a fun and inexpensive rifle to put ammo downrange with.
Seems like the colt patterns can be built off of a standard forged 223 lower, just needs a different set of machining steps to finish it.