I believe that the Soviet PTRS-41 and the British Boys need to improve the performance from the beginning with the technique.
Step one! It is necessary to increase their damage to 100-120. Why?
Pancergrenadiers are armed with two Panzerschreki which makes them more effective against the Tanks and cars, and they also have STG-44 (effectively at any distance) against the infantry. These are universal troops.
Make the Soviet PTRS-41 and the British Boys more effective against infantry and easel guns. Accuracy against infantry by + 25% - + 35% and easel guns increase accuracy by 45% and damage by 25%.
Step three! We are removing the Soviet PTRV-41 from the Penalty and Conscripts Squad. Since there are Universal Soldiers of the Red Army, these are Guardsmen.
The British Boys can add to the second commanders or change.