Nice bank acct lol, highest I've saved up was 3 million, which was promptly spent on my M40/43.
What's a decent 122-44 match look like for you as far as credits?
I've had a few 100k plus gross games which will net around 70-80k. Those games however are few and far between. I usually net 15-35k on a decent game, and 50k+ on a good/great game. I have a premium account though, so if you have a regular account shell costs can significantly impact your net credits.
I run 50/50 regular/premium ammo, so on some games I run out of regular ammo, and only have premium left, which cuts into the profits. Regular shells aren't cheap either at 1k, and since you can lob them every 6.6s you can go through quit a few of them. Also since the accuracy isn't that great and niether is the pen, you'll have alot of misses/no damage shots, which kills your return on investment.
It wont make as many credits/game as the tier 8 premiums, but its significantly cheaper gold wise. That and you can use it to train your 268/704 crews (minus an unlucky loader).