No mention of it in the ATF state laws and published ordinances for firearms.
But, I think you will find it is a federal law regarding the importation and selling of imitation firearms, this is not the jurisdiction of ATF (along with the whole orange barrel plug, not mentioned in the ATF guidelines but still a federal requirement.)
Also, there may be state laws that govern the selling and importation, that differ from state to state.
But, according to the letter to me from San Francisco, CA, customs, the imitation firearm must have a fully plugged barrel, and be painted orange at the tip to be imported (mine was not orange painted and forward firing with 8mm blanks.)
When I spoke to the Customs guys personally, it was easily smoothed out, as the gun was for a motion picture production and not for resale. I did have to provide quite a lot of written proof, but this should be easy for you, too Kevin, as we actually do this stuff for a living.
PS. When your property is seized in this way you have a very limited time to act, or they are permitted to destroy the goods. No joke, this was in black and white, on the letter that was neatly inserted into the empty gun box that arrived from Turkey.
I haven't encountered an ATF, Sheriff, or Police officer who was interested in the difference between forward or side venting blank firing replicas. Their concern has always been for the security of the actual live weapons and paperwork going with them, in the case of assault weapons (in CA) or fully automatic/NFA weapons. But, most importantly, in the paperwork of the person assigned to handling the weapons to and from and on set, and my filming permits for the location.
Incidentally we have a new issue here in CA, actors with criminal records dissallowing them from owning a firearm are now not allowed to use them on set, I'm not sure how this will be upheld, but it's there in black and white in the rule book.
There goes half of my regular cast!!!
JJ