Tiriaq is correct. Plainfield barrels do not have skirts on them. Plainfield built this little feature into its (cast) receivers, so a USGI or an aftermarket barrel with a skirt will not screw into the receiver completely and clock up properly. The skirt has to be carefully removed.
What is on the receiver? Is it the little support web on the extended area for the trigger group to lock into?
Or something completely different.




















































