The build for Striker is around 6k Stamina instead of 9k. The reasoning for this is because, in PvE, 6k Stamina healing is more than enough and allows you to dump main stat into Firearms and Electronics in order to increase damage as well as unlock talents such as Ferocious.
Lightweight M4/LVOA-C: Your primary weapon for middle to long range. Use it primarily to continuously build signature skills with Determined. Roll Destructive and Ferocious to maximize damage against Elites and Veterans.
Showstopper: Your secondary weapon to use at close range. Roll Responsive and Destructive because Responsive is pretty much a must for shotguns.
Pistol: You can re-roll Expert off the Pistol if you wish but Coolheaded is a must to have if you need to build signature skill quickly and can switch to your Pistol.
Flashbang: You can switch Flashbang out to a Support Station Immunizer if you prefer. Flashbang is very nice to run just because it provides a really good way of crowd control in Legendary missions and other PvE activities.
First Aid: For when playing solo, you can run Overdose as a mod. For a team environment, switch it over to Defib to be able to revive teammates as well as still being able to get a source of heal over time with how strong the healing from Defib is.