The 'V' is the proof mark.
Some more info for you from an example in the Springfield Armory Museum:
U.S. MUSKET MODEL 1812 TYPE I SPRINGFIELD ARMORY FLINTLOCK .69
Manufactured by Springfield Armory, Springfield, Ma. in 1814 - Standard Model 1812 single-shot, muzzleloading, flintlock musket. Iron furniture. Metal parts finished bright. Three bands, spring fastened with upper band double-strapped with brass blade front on lower strap. All three band springs located behind bands. Button head shaped ramrod. Cheek recess left side of butt. Bayonet lug top of barrel approximately 1 1/2" from muzzle. Weapon weighs approximately 9 3/4 lbs. Generally patterned after the M1777 French flintlock musket. Adopted as standard on December 8, 1812, by order of the War Department. This is one of 7,379 weapons manufactured in 1815.
I would say that you have come into possession of a somewhat rare weapon, Considering less than 7500 were made in 1815, and who knows how many of those exist today, conversion or not. Yours has some furniture missing from it, to go along w/ the condition. Still AWESOME!
(I'm pretty sure yours is the type-2 although most of those are stamped 1816..)