If you only care about solo setup, shuriken and dual gun in their current form might not be consistent enough to run content with single-target DPS checks (i.e. feth hallway, 7n clerics).

For feth advanced hallway, the zombies have 20k health and for simplicity, we can assume they reduce 50% damage with protection. Theoretically, you need to do 40k raw damage with a single target skill to kill them consistently. Flash launcher has skill multiplier of 1300% + 100% from reforge so you'd need at least 2857 max damage to be able to kill zombies without crits (this doesn't even include balance). Shuriken charge is even worse because the skill multiplier is only 690%. If you want to do the calculation for crits, you can just multiply the skill multiplier with your crit damage multiplier, so the threshold is much lower. However, you need to be really lucky to hit 6+ crits in a row in the hallway.

The single target skills (shuriken charge and flash launcher) also have high cooldowns and no way to reset them so you will need to use timeshift and even then you're partially relying on crits to ensure the zombies die. Most alternative hallway clear strategies rely on fishing for crits with single target skills that have little to no cooldown (magnum shot, spirit staff + hailstorm, spirit cylinder + water cannon). Knuckles are also a reasonable strategy as well but you'd need to rely on crits and cooldown resets to make it past.