Just about to dig through this thread. I'm currently stateside with my Tavor and my US paperwork.
... 30 seconds later ...
Okay OP, can you clarify what you mean by disallowed?
Did you already have a Form 6NIA with your Tavor on it?
Did the ATF contact you to revoke or modify your Form 6NIA?
Simple Sum Up:
As far as I understand it the ATF lists 3 models of Tavors out there.
1. The IWI US "SAR-21"
2. The Israeli Military "TAR-21" which is generally on the ATF's "machinegun list"
3. The Civilian "TAVOR-21" model you find in Canada. Should be stamped right on the side of your gun.
When I applied for my Form 6 earlier this year, I had to call into the ATF, then email back and forth a bit with them. They wanted to make sure that my rifle was a semi-auto only setup, and not an NFA controlled item. I told them a bit about my rifle, how long I'd had it, what I'd done to it, then I emailed them external photos and they issued me the temporary import permit.
That + a match invitation has served me well when crossing the border. I literally made the crossing Monday afternoon. Standard procedure: declare everything, open everything up for the border officer, let him compare the serial numbers on paperwork to serials on steel, have a short "That's a damn cool gun" conversation, and I was on my way.
Curious to hear more about who's telling you your rifle has been "disallowed." Also keep in mind that my experience only applies to temporary import. If you're moving to the United States that would be a whole different barrel-kettle of fish-monkeys.
