The problem with the Penal PTRS, however, and why it could maybe have 3 is that the Penal PTRS squad doesn't scale really well into late-game. It's not incredibly dangerous to armour, it's snare while potent - is short-range and you're giving up an 8 population 300 manpower tier-locked squad to light anti-vehicle work that falters against infantry the moment it takes losses and the unit often doesn't have enough time to sustain DPS before getting butchered.
I can see the need for increasing rate of fire, but at the end of the day, it's essentially a dedicated AV squad so it does need to threaten vehicles later in the game.
New T3/T4 upgrade, "PTRS training", PTRS does what PTRS does for guards in soviet campaign.
Tho, it would really be amazing if penals weren't complete meme in late game, both AI and AT option.