Not a lot I can say about this barrel, the pictures speak for themselves, both pieces fit together very well. This barrel will enhance the Revell kit no end.

I don't have any exact measurements of the gun barrel, but the barrel matches several sets of drawings that I have, I presume that it is the correct length.

References

Drawings from the Concord Warrior British tracked combat vehicle by Carl Schulze

George Bradford Drawings

Drawing in the MAFVA magazine Tankette