H&K USA Arlington to Chantilly move?

[Valmet]

Wondering approximately when H&K moved their US offices from Arlington to Chantilly VA? I have a late Benelli 121 Riot and gun is marked Arlington while paperwork is Chantilly. Thanks in advance folks

 

[AGG]

Security Arms Company, Inc. (1974-1979)
HK/Arlington (1979-1983)
HK/Chantilly (1983-1988)

Texted you on other information.

Tony