Base Kit: Tamiya, PCM, others
Master Model produces some finely turned brass barrels for aircraft and ships in a variety of scales. One of their latest offerings is a barrel set for the Spitfire 'e' wing. There are a total of 6 parts - 2 cannon barrels, 2 fairings and 2 .50 caliber barrels. The .50 cal barrels are designed to fit snugly in their fairings, which they do exactly.
The barrels are perfectly turned, the details are very fine and will avoid the issues associated with eliminating molding seams , such as ending up with an oval shaped cannon fairing (been there, done that). I pulled out the kit barrels from the latest Tamiya Mk. VIII as well as the wing and barrels from the Pacific Coast Models Mk. IX for comparison's sake. The Tamiya cannon are very finely detailed themselves down to the drilled out barrel, but clean up will still be a chore. The PCM kit part has much softer detail and needs drilling out and careful clean up as well. The Master-Models product is ready as is with no clean up needed.