WHAT DOES BCM LOWER RECEIVER MEAN?

bcn complete lowerWonderful item. Only blem is a little scratch on the top in the qd end sling mount with the castle nut. No big deal to me and saved $ninety. More affordable than setting up my spikes tactical lower with bcm elements. As well as you receive a stacked castle nut plus the qd sling attachment. Glad PA obtained these in inventory.Websi