Drweiler,
They do indeed have mixed reviews. I am told that "good" quality lower receivers (as of last gunshow) were going for $550... stripped.

However, I am more interested in the finish/ quality of your lower. Could you post additional photos? Mine has a plethera of machine marks and looks more rough in some areas... that you won't see in "premium" lowers.

BTW, mine starts with a KX and was purchased during the Clinton ban era. Model is: PCR 99.

Not sure what the model numbers actually mean... but your SN indicates a 1993 (?) date of manufacture...

What does my serial number mean?

Perhaps you have another "Manufacturer Sample"... but their list doesn't mention anything in the SN range of your rifle.