Interesting thing is that where I live, supposedly the head of local law enforcement has to approve purchase (or possesion) of Class III weapons and suppressors. Our police chief has stated in public forums in our community that he wouldn't approve one.

Q: Is the chief law enforcement officer required to sign the law enforcement certification on ATF Form 1 or ATF Form 4?
No, law enforcement officers can be compelled to sign the law enforcement certification under Federal or State law. However, ATF will not approve an application to make or transfer a firearm on ATF Forms 1 or 4 unless the law enforcement certification is completed by an acceptable law enforcement official who has signed the certification in the space indicated on the form. See “What law enforcement officials’ certifications on an application to transfer or make an NFA weapon are acceptable to ATF?” for more information.

Q: If the chief law enforcement official whose jurisdiction includes the proposed transferee’s residence refuses to sign the “law enforcement certification,” will the signature of an official in another jurisdiction be acceptable?
No. But see “What law enforcement officials’ certifications on an application to transfer or make an NFA weapon are acceptable to ATF?” for the list of acceptable chief law enforcement officers.

Q: What law enforcement officials’ certifications on an application to transfer or make an NFA weapon are acceptable to ATF?
As provided by regulations, certifications by the local chief of police, sheriff of the county, head of the State police, or State or local district attorney or prosecutor are acceptable. The regulations also provide that certifications of other officials are appropriate if found in a particular case to be acceptable to the Director. Examples of other officials who have been accepted in specific situations include State attorneys general and judges of State courts having authority to conduct jury trials in felony cases.

[27 CFR 479.63 and 479.85]