Vanguards are NOT built by Howa anymore. In the late 90s Ed Weatherby decided to move the production of these rifles back too American shores
The production of mark V's was moved back to the states and unless the situation has changed very recently,they are being built by a contractor named SACO located in Maine.The vanguard is still made by howa as is stated below
The new Vanguards use a black synthetic stock in the modern classic style. This Butler Creek injection-molded composite stock is checkered, has excellent lines, and comes with a recoil pad . . . .
. . . All Vanguards are based on an action using a one-piece forged and machined, flat bottomed receiver and a machined steel bolt with dual opposed locking lugs. This modified Mauser action is built by Howa in Tokyo, Japan . .
The above quote was taken from an article found at the link below
http://www.chuckhawks.com/wby_vanguard_syn.htm
I doubt they would do that on something that someone else builds, but who knows nowadays.
Weatherby does not manufacture their own rifles and that includes the mark V.