Since you bring "balanced around PD2 LMG mechanics" i don't see how 30 round "LMG" could work in PD2. So for having much smaller magazine you gain accuracy/etc but you cant utilize it fully since you're not allowed to use sights/bipod and you end with not effective psedo-LMG. At least that how it was when i tried idea of "STK Ultimax 100 Mark 5".

The STK Ultimax 100 Mark 5, thats a good LMG and if you make it with bipod and grip attach would be great, multi purpose combat LMG!  STK Ultimax 100 Mark 5STK Ultimax 100 Mark 5

Did you not hear a word he said? He did do it, it just didn't work well so it was scraped. It just becomes a Psedo-LMG like the Bootleg, except it can't aim and can't use a Bipod.