It was as of printing of the Index, but
GW have
FAQ'd it with the following:
Page 158 – Wolf Guard, Wargear Options
Replace the first three wargear options with
the following:
‘• Any model may replace its boltgun with a plasma
pistol, storm shield or an item from the Space Wolves
Melee Weapons or Space Wolves Combi-weapons lists; it
may also replace its bolt pistol with a plasma pistol,
storm shield or an item from the Space Wolves Melee
Weapons list.’