I've now moved onto the turret and started by removing all the details that need replacing. A new rear plate was made up from plastic card too. Again the cast off stuff needs loads of clean up and tweaking to get a good fit. In the end I used an Accurate Armour barrel as the cast off version was so badly cast clean up was impossible. Far to many pin holes, mould lines and warping to sort out. I think as the set is very old the moulds have not been updated for some time hence all the clean up and deformed parts.
Shame really as the newer cast off sets are really excellent, this set has been a big disappointment so far. Anyway rant over back to the build and the barrel, I added a metal tube into the gun mount and a length of plastic rod in the end of the barrel too. This gives me a nice positive fit and also enables me to add the dust cover and sort out the detail on the gun mount before adding the barrel. Quite handy later on when it comes to painting.