You can very easily convert models from the Ork Boyz set to create your own Orks with Heavy Shootas.
Basically it consists of using two Shootas to create a Big Shoota. You may also notice that the head is from the WHFB Orc Warriors sprue.
Here’s another version.
I started off with a black undercoat and then did all the metallic bitz with a drybrush of tin bitz and chainmail.
Here they are with the metal bitz done and their basses flocked.