I did a bit of poking around and found this-
http://www.etsy.com/listing/77966420...and?ref=market
It says it is a vintage 1984 transforming robot and rifle cap gun (called RO-GUN RGX-V1) by a company called ARCO.

The same searches also turned up similar RO-GUN cap gun and water pistol robots made by ARCO which were labelled as GOBOTS, so at a guess they were under license to make them for Tonka back in the 80s.