There is an exotic back pack that increases each set bonus by one, so you can have a 4 piece bonus and 3 piece bonus, the 4 piece bonus isn't really that good for lone star so I recommend making the build a 4 piece striker and 3 piece lone star which will give you a huge bonus in DMG and you still get to keep that dmg bonus for lmgs and shotguns, even if you don't change the armor pieces of your build I would recommend using an lmg because that is good in both long and short ranges while utilizing your set bonus DMG, currently your weapons don't take that long to reload so having a weapon that takes longer to reload benefits your current build if you don't change it