My notes show that the development Yak7B's were originally equipped with 6 rockets or 2 x 25 to 100KG bombs. It under took trials in April 42 but upon entering series production (May 42)the rockets were dropped from use but the bomb racks remained.
Gordon & Khazanov:
Following state acceptance trials, the State Defense Committee issued a directive that Yak-7A production was to be converted to Yak-7B. As early as April 1942 the first production Yak-7B was rolled off the assembly line at
Novosibirsk Plant No.153,and the fighter at once began to reach the front line units. From late May the rocket projectiles were removed to improve performance, though the under-wing bomb racks were retained.So, from this I understand that the initial production aircraft (~month's production) was equipped with the rockets. Of course those didn't yet have the M105PF engine our Yak has based on its performance. When the Yak-7B was starting to come with the M105PF they also removed the wiring for the rockets and therefore removing the provision for rocket completely.
So, as Tilt said it would be correct to remove them and add the bombs instead as we have a slightly later production version in AH but a small number went to front lines with the rocket rails.
