Firearm Proof Marks, Arsenal & Inspector Marks

		Preliminary black powder proof mark
		Final black powder proof mark for use with nitro powder. The same mark was also used for the final proofs with black powder for smoothbore muzzleloader barrels.
		Inspector or "View" mark which was applied after final proof.
		Applied only to barrels of rifled military arms that had passed nitro proofing.
		Semi-smokeless proof of all guns.
		Voluntary special proof testing with extra heavy loads. This mark appears with the standard marks and standard load marks for the caliber.
		Re-proof mark, seen on black powder rifles which had been proofed with nitro powders. These guns will also have the "NP" mark. Seen on repaired guns that required re=proofing.
		New rule called for marking of gauge along with shell length for smoothbore barrels.
		For rifled barrels, bore diameter and case length must be marked.
		All foreign barrels and complete guns not bearing proof marks acceptable by British Proofing Houses must undergo testing and are then marked with the standard proof marks in a heavy circle. "NOT ENGLISH MAKE" will be stamped with letters being light on a dark background.
		The Gun Barrel Proof Act of 1950 announced henceforth all chrome-plated barrels or otherwise treated should be considered un-proofed, therefore will have to be proofed. The new Act also made several changes to the Gun Barrel Proof Act of 1868 that had been ignored for sometime. See listing below as the rules apply.
		British Proof Marks 1868 to date.
		Temporary proof mark used since 1856.
		These are the final black powder proof marks. The London mark was in use since 1672 in this or similar form. The Birmingham mark was valid from 1813-1904. Since 1925 the London mark was used on semi-smokeless as final proofs for shotguns with the "NP" mark in conjunction.
		Inspection mark, London - since 1672. Birmingham - since 1812-1904.
		Final black powder proof, Birmingham 1904-1925. Then used with "NP" mark for rifles proofed with nitro or semi-smokeless powders.
		Birmingham inspection mark used since 1904.
		In use from 1868-1925, this mark was used to show a single final proof with loads designed for temporary or provisional proof.
		Semi-smokeless proof for all guns in use since 1904.
		Mark indicates gauge prior to 1925, a 3-inch chamber, but after that year chamber length had to be indicated in inches.
		Mark indicates gauge in used since 1925, and shows that the chamber is longer than 3-inches.
		These are the proof marks used for choked-bored barrels between the years 1875-1887.
		These marks where used for choked-bored barrels between the years 1887-1904. Since 1904 the word CHOKE was added. If the choke is 0.008 inch or more, marking is obligatory; if less it is voluntary.
		Designated for Express rifle barrels in use from 1878-1904.