@makman,
there is another model of the barrel-type DCs in the guns_uk.* library that comes with some of my ship models. The 3d model is by Alex, I re-textured it a bit. Also, I transplated it into DC_R_KG.* library for private use:
If you like it, send PM.
@padi,
Jeff hint is great. I use his idea to reduce the file size of my ships since a while.
If you do not have GWX at hand, just check for boats and optical instruments, such as air spotters, of Isaac Sweers.