If the length of the barrel is 16' or greater it will be a rifle. Barrel length determines rife/pistol catagory, unless it's an SBR. I found this question posted elsewhere and I believe it is correct:
I understand that according to the BATFE a rifle's overall length ?Efor a rifle with a folding stock ?Eis to be measured with the stock extended. I have seen a number of examples that would tend to support this but I cannot find anything in the United States Code, the Federal Register, or any published letters from the BATF/E to support this.
I also see on this site where James Bardwell has been quoted as stating this to be a fact. I understand that 27 CFR 179.11 states that the "extreme ends"of the weapon are to be measured but I am looking for an official recognition that this means "with the stock extended".
If it were to be registered as a pistol you would have to remove the buttstock and make it so one could not be attached at anytime in the future.
I think you are getting the run around from your dealer
Call Century or better yet the BATF and get a letter from them stating this is correct.