After the murder of Ranodip Singh Kunwar in 1942 BS, his father, Bir Shumsher, became the nation's prime minister, and opportunities popped up for him.

At a tender age of 14 years, he was appointed to take care of the ammunition department in the Royal Nepal Army.

[3] At some point, Gehendra Shumsher worked as a spy chief and the head of police, but his interests were largely confined to the manufacture and design of firearms.

So, after a considerable study of British catalogues, he set up manufacturing factories at Jamal (Seto Durbar), Sundarijal, Balaju, and Megchan (Bhojpur) with a view of doing just that.

Besides, he set up a seven boiler rice mill and wind motor to draw underground water at Seto Durbar, the residential palace he inherited from his father.