Master Models has released a set of 8 machined brass gun barrels for the current batch of 1/32 scale P-47 kits. One nice thing is that these barrels will fit either the Hasegawa release or the Trumpeter release.
The barrels are perfectly made and already have the ends drilled out. The attached pictures show a comparison to the Hasegawa barrels, although there is really not any comparison – there are no seam lines and they have no sprue points to sand down.
There is a 1:1 scale picture showing the proper alignment. To use this set in the Trumpeter kits, simply paint and glue the barrels in place. The Hasegawa kit will have to have the bulkhead drilled to accept the barrels, which you can then paint and glue. The drawing will then insure proper alignment.