I think the AT capability of the SU76 is just not worth getting it due to better options. Buffing accuracy or pen on the other hand might screw Ostheer. If we want SU76 back in the meta (which it is not currently, as no one builds it), we should give back some utility. 20 mun barrage, as I said multiple times, is my suggestion.
I don't think that decreased cost of barrage make it popular. Problem as always in overall effectivness of unit. If you make barrage more user friendly (more accurate or more AOE) it could screw german infantry due to wipes and i don't think that this will be good in terms of balance and gameplay. SU-76 became a prey of soviet design - it trying to become good in any role, but fail, due to bad stats and more better units (Zis). It also don't have any chances in lategame - it means that it place in early-midgame, but as i previous said, these timeframes of games too short and SU-76 can't fit to it.
I recently saw Skippy game, where his team try to did heavy SU-76 spam - against 1 p4, 2-3 su-76 works, but when p4 2 or 3 or panther (or any another heavy) came to field, they light is off. While barrage quite effective vs blobs, SU-76 leaded to very later T4. And as result game was lost, because map pressure was lost and loses of su-76 leaded to huge fuel drain.
If it’s supposed to be a premium ATG, what if we made it so it could be killed by infantry from the back? It is open backed, and then it could get a buff to its damage (120 -> 160) or a cost reduction
It's squishy enough, if we make it more fragile, how you supposed to play and what compensated this? In game only rocket artillery very fragile, but it's compensated very strong abilities to wipe enemy infantry and team weapons.
I think about several possible ways:
1. Change of role could return it to game - make from SU-76 light howitzer for indirect arty support (what it did in real life). While T-70 is fast, moblie and aggresive AI, SU-76 became more defense-style, like mortar do.
2. Make separate upgrades for it. Like:
"Tank hunter":
Increased pen (+20) and damage (+20).
"Tank Hunter Ambush Tactic" stealth (with 1-st shot 10% accuracy and 10% pen bonus, rotation speed decreased by 60%).
Timed 20s (like HEAT OKW shells) ability to
"Tracking" enemy armor (like m-42 munition ability). Barrage have increased cost to 45 and fire only 2 shells.
"Artillery support":
Give it more powerfull HE shells for
"Supporting Fire"-increased cost of barrage to 45 and work like JT HE barrage.
"Piercing Shot" (like ISU-152 have with 50% penetration bonus).
"Smoke barrage".
Regular barrage become free, but share cooldown with "Supporting Fire". Penetration medium decreased by 10, far penetration by 20 to show SU-76 how infantry support unit.
Su-76 could equip only 1 upgrade.
Separate upgrades could help player to choose what he want - more AT specialized unit or more AI or still it like it is. Maybe add new ability for all variants like
"Overdrive" that increased rotation speed by also decrease accuracy to slightly help to survive due low armor and health with bad pathing..