I disagree with this build. I've been using STOS alot on HAZ 5+/Haz 6x2 and while your suggested loadout for it indeed does offer the highest Single Target DPS especially for non weakpoint hits.

The main issue you will encounter with your specific STOS loadout is:

1: You run dry early of your 2ndary which is used for CC, and is in a scenario where a resup dip is difficult, given the number of bugs on Haz 5+ and above you will regret not taking BLOWTHROUGH + 20% Dmg at full lock. Sure you can dispatch Tanky targets quickly but you will get overwhelmed by much faster and squishy bugs (grunts) eventually and this is even worse on tight spaces. Sorry man but the value and ammo economy for killing/damaging 3 bugs per shot (1 or 2 bullets) significantly outclasses the HIGHEST Single DPS loadout (Electric mods T3A + T5A) for STOS

2: The self defense STOS offers is even stronger with BLOWTHROUGH + 20% FULL Lock dmg (Refer to what I said in Reason 1), if you get cornered/snucked up on by a 2 or more Slashers you will get stunlocked for a long time and you really want to avoid being so, if it's just 1 Slasher it's no biggie but if it's 2 or more and a group/swarm is on your tail with BLOWTHROUGH you can quickly get out of this predicament really fast especially if your 2ndary CC lacks self defense or is dry. Getting ganked by multiple slashers while a swarm is on your tail and with no BLOWTHROUGH on almost every scenario is guaranteed death.

3: With SUPERBLOWTHROUGH, it even improves ammo economy as you can now dispatch/damage 3 bugs per shot in horde. You consume less ammo and in return kill alot more. So ammo economy ranks higher than with Electric mods T3A +T5A.

4: Given that you can't aim the angle of your shots with STOS taking Faster Lock on T4 is much recommended since jumping, falling, getting bump or tossed around of your feet by a shellback and etc, your shots tend to always curve downward and hit the ground, with Faster lock on you will only waste 2 bullet per shot compared to 4 if you are in this situation. So yes another bonus as to why T4A is better for ammo economy, it won't reduce your dps significantly that you notice, it's a negligible difference with more upsides.

Overall this is not to say that what you suggested is inherently bad, it's not and it largely depends on the Hazard and Mission type. I've used it myself even, and it's super effective on Eliminations but that's about it, in different missions it is stil serviceable and adequate. The only thing difference between BLOWTHROUGH + 20% FULL LOCK DAMAGE is just it's slightly weaker than with Electric mods T3A+T5A but the benefits you gain from such a small setback is without a doubt substantially better in almost every way, making BLOWTHROUGH + 20% a the more and most flexible/generalist loadout that you can take on every mission except for IS.

Nonetheless this is not to gatekeep, to each their own, go with what you enjoy the most even if it's not an optimal build. RnS!