no!
Having work for the past 3-4 years in a gun shop does not make me an expert on the subject; however it does give supprising insight. You will love this.
Most gun retailer, IE places that sell guns, make up, or missinterpet, or are ignarant of gun laws. That employee probly heard some story some where about "assult rifles" and decided that this is what is ment. Forgoing the fact that the sig 556 is not an assult weapon (I just could not get mine to shoot full auto no matter how hard I pulled the trigger!) It will transfer just like a rifle. The only change the AFT has made recently in this area that would be even close is that now a stripped lower reciver from an AR-15 can only be transfered to a person older that 21. This is because it can be built into a pistol.
These people simply are to ignorant to take the time to learn about their job. But don't feel bad because tomorrow they will be in the footwear department. It is sad that more than 50% of the gun shops I have been to; if you stand and listen for 20 mins, the employees will either lie, say something incorrect, or just make stuff up. Most people don't have the charerter to simply say "you know, I just don't know that one let me look it up." Instead they make something up, and "oh it's the law!"
Buggs me to no end.
as I am sure you can tell