The gun

“203 mm howitzer M1931 (B-4) was a 203 mm Soviet high-power heavy howitzer. During the Second World War, it was under the command of the Stavka’s strategic reserve. It was nicknamed ‘Stalin’s sledgehammer’ by German soldiers… This weapon was used until the end of the war in the Battle of Berlin where the Red Army would bring these guns up at point blank range to smash German fortifications with their heavy 203mm shells.” [1]

The kit

Trumpeter 1/35 kit [2].

References

1. https://en.wikipedia.org/wiki/203_mm_howitzer_M1931_(B-4)
2. https://www.perthmilitarymodelling.com/reviews/vehicles/trumpeter/tr02307.html