welded, usually TIG-welded, not JB-weld.
I am still waiting on the written policy from HPD on having to weld it. The statute only states "detachable". Any verbal statement from HPD on the welding of the magazine to the lower is void without written policy from the AGs office or written into the statute itself.
So I would just bring your stripped lower with cheapo magazine and bullet button installed to HPD to register it as a pistol. When asked where all the internals are, tell the truth... Its being built as a pistol without a detachable magazine. Have the below statutes with you as legal basis. Now if they decide to confiscate your lower that hopefully you purchased for about $50, you have grounds to bring suit against HPD for theft of a firearm (Federal crime - call the AG & ATF, they took your firearm without your permission and get the officers name and badge#) and denial of rights under statute. JUST BE VERY, VERY POLITE AND COURTEOUS. You don't want to get arrested for being belligerent. Say thank you and walk out the door and go forth and file suit should you so choose. (Remember, this is not legal advice, but I did stay at a Holiday Inn Express. Your mileage may vary)
California (in the 9th Circuit) and Maryland definitions of “detachable magazine” are included below.
a. California, Title 11, Division 5, Chapter 39, Department of Justice Regulations for Assault Weapons and Large Capacity Magazines. ARTICLE 2. DEFINITIONS OF TERMS USED TO IDENTIFY ASSAULT WEAPONS The following definitions apply to terms used in the identification of assault weapons pursuant to Penal Code section 12276.1: (a) "detachable magazine" means any ammunition feeding device that can be removed readily from the firearm with neither disassembly of the firearm action nor use of a tool being required. A bullet or ammunition cartridge is considered a tool. Ammunition feeding device includes any belted or linked ammunition, but does not include clips, en bloc clips, or stripper clips that load cartridges into the magazine.
b. Maryland, MD Code, Criminal Law, § 4-301: Definitions - Detachable magazine: (f) “Detachable magazine” means an ammunition feeding device that can be removed readily from a firearm without requiring disassembly of the firearm action or without the use of a tool, including a bullet or cartridge.