Green engi but guides with no playstyle are a bit weird to me. How do you play it? Is this just close range spray n pray? The spread on the stubby is quite big and the damage doesn't really seem that amazing unless you're in the middle of the chaos. Breach T5C is also a bit of a question mark. The trail does waaay more damage compared to the tripple split, as long as you can hit your shots I rarely find the tripple useful and I run though way more ammo to make up for the trail dmg loss.
Weakpoint bonus are not flat across enemy types. Mactera Bluks and Breeders take x3, grunts take x2 and praetorians/oppressors take x1. If you can hit your shots T4A is always better.
If you don't take T1B then T4B is garbage. You need to electrify a target before you even get the effect. 25% sounds like a lot, but it isn't. You frequently shoot 4-6 bullets with zero benefit. They could have all, instantly, enjoyed T4A. Also T4A helps vs targets that you cannot electrify such as an oppressor.
Bilbo Sandbaggins
Stubby without electric CC is garbo in haz5 and the accuracy is too mediocre for DD+hollowpoint focus. As a result, this is also highly ammo inefficient because you aren't spreading that AOE electric field. This is for greenbeards or people who intentionally want to run inferior builds