PICA bans lower receivers which can be used to build AR-15s or other rifles. The existing ISP process requires that these be declared as weapons, and that a caliber be specified.
If a stripped lower is stamped as "multi" and has never been built out into a rifle or pistol with a specific caliber, there appears to be no way of complying with the law without providing false information to the ISP. To complete the process, you have to specify a caliber, and any caliber you choose is arguably wrong. This may sound like it's making a big deal out of nothing, but the ATF regularly revokes FFL licenses for less significant paperwork errors, so in the current environment it's a legitimate concern.
My take is that this is either a gap in PICA, a gap in the emergency regs, or a bug in the implementation, but I have no idea which. ISP advice is to just go ahead and pick something.
Any advice?