Originally Posted by IXLR8
I would be careful about change if it includes a change in caliber. If you change from a .223 to a .300 Whisper/blackout, and your paperwork is challenged, and it is clearly marked .223, there may be a problem. Some people have submitted paperwork with multiple calibers, but lately I have seen that paperwork kicked back allowing only a single caliber to be specified.
You cannot submit multiple calibers, you cannot put multi in the caliber spot on the paper work.You have to choose one , doesnt matter if its .223 or 5.56 but it cannot have both on the paper work . This is where it gets tricky for .300 blk. put .300 some agents will let .300 blk slide some wont . All this will get your paper work sent back to you and just delay your stamp . YOU CAN put what ever caliber upper other than what the paper work says or any size barrel length on the NFA lower without any issue so long as its not a permenant change . Permenant changes must be notified to the BATF via a phone call and letter . I own 3 sbrs and have 2 pending . Im not the know it all about sbrs , but I have had my share of paperwork returned also. They are all of a sudden picky about fingerprint cards , so when you decide to do it make sure to order NFA fingerprint cards from them . They are free , we already pay taxes for them .