I am in the market for a dedicated 9mm lower for a new build. I found one at RRA and CMMG. I want a stripped lower so I started my pursuit for a CMMG because I can get it at a local vendor. I am somewhat perplexed as the person at this retailer is telling me the lowers from CMMG are not ban compliant. All I want is the stripped lower. What can be non-ban-compliant about a stripped lower? Is there something unique about their 9mm lowers? I have asked the retailer but I am not sure my point is getting across. I asked specifically for a stripped lower and was told CMMG lowers are not ban compliant. I am confused. Any insight will be greatly appreciated.