Yep - you need the guys (both riflemen and tankers) to survive long enough to get to 70 plus experience, and 3-5 kills or so helps this process. once they are there, they are
noticeably better than the 57-61 or so they start off at.
The 45mm gun is reasonably effective even frontally up to 300m or so as and until the 5-7 front armour P3s and long 75mm P4 start arriving in mid 42 or so. After that, you really need to fight German armour from short range side attacks. Luckily, they are only around 3 side armour. Even later on the 45mm should be useful, as Panthers are but 5 side, and I should habve T-70 with some APDS by then. (The T60 is useful as infantry support, bought with support points, but I do not see these as forming any part of my core force).
Once you can get the Zis-57, a section of 2 added per tank coy, with a section of kosmolets ammo carriers, if used skilfully is a good boost to a light tank coy. (Less so if BT tanks trying to advance fast though!). A hard-hitting and accurate little SP-ATG. But slow, low ammo, and open topped.
(NB - We made the experimental T-50-57 available for what-if. Only one made, there were problems with fitting the 57 in such a small turret, and the 57mm HE shell was always poor, plus there was never a reliable supply of the APCR round. At the cost, I think I would rather have a T-34 instead though!
)
I have got a 76mm ATG platoon in the core, origianlly truck towed, now halftrack. Rather useful, even if attacking I push these forward to provide long range overwatches.
I had a section of T-28e to accompany each leg rifle coy, these are now (Late 42, entering Stalingrad battles) M3 Lees, and these are reasonably efective as infantry close support tanks if kept away from any long-75mm German armour.
I bought the infantry batallion support coy as I had 3 rifle coys. Initially I thought the HMG would all be upgraded to AAMG. However I have found that massed HMG are brilliant for defence, and supporting an attack as well. All now 12.7 Dushkas, for really long range support fires - both direct and Z-fires.
Cheers
Andy