Here's what new PTRS dps should look like roughly:
PTRS Penals didn't get better performance against infantry outside a negligible amount after 35 range.
3x new PTRS aren't even equal to 1x SVT, let alone if you add the dps of 2x old PTRS to the 1x SVT.
PTRS Penal squads might not had the AI increased but they got their AT increased without any loss in AI and that is just one in series of buffs.
Difference is not DPS at vet 0 is a combination the DPS and high accuracy bonuses the unit gets and other bonuses available to the faction.
Once vetted the new Penal PTRS should have similar accuracy with one guards use at max range.
And wly should a unit that can fight vs mediums tanks retain good AI DPS in the first place?
The idea that Penal should cover all the needs of the Soviet faction in AI, AT, Anti-building and Anti-garrison with a dirty cheap tech cost is simply flawed to begin with.
As for the AT capability here is a fast test I did, of PTRS Penal vs PzIV and AT PF vs T-34 (both infatry where set to no damage) where the two tanks died almost simultaneously after driving toward the AT infatry:
https://www.coh2.org/file/19308/at.jpg
(anyone who want to be more thorough can repeat on his own multiple times and provide and the results )