This vehicle is currently featured only in one map, when there were over 1,300 produced and they saw action till the war's end (nearly 300 were still in service, April '45).
If the gun could be revamped slightly to match some of the reports from 1944:
The Army Group Ukraine South, 9.1944;
"The Assault Howitzer continues to perform brilliantly. Ricochet fire has great effect. Successfully defeating tanks at up to 1,200 meters. Concentrated fire of several Assault Howitzers proved highly effective against large pockets of resistance."