@Luciano, hope the information helps. I have only found mention of 7 x 20mm on the USS Hoel other than the website you found. Your PE work is looking great. Question, what blackening agent do you use and what does it do for you? Does it make the paint stick better?
OK, so here is a USS Dace update.
The front bow is finally reattached.

Now I am adding the hull ribs that separate the torpedo tubes. Figuring out how to do this has been a big challenge. Hopefully the final result will look good.
With the ribs drying I started on the two 40mm Single Barrel Bofors.

Sorry for the blurry picture but you get the idea. I used the Master Model 40mm Air Cool Barrels. Very challenging drilling the hole to mount the barrels. I see a little gap in the picture. Hopefully the paint will make that disappear or some white glue.
A little more PE work on the bofors and they will be ready to mount
I should receive the 3d printed pieces I need sometime this week and I can get moving along more on the Dace.
Great looking builds all around, so much to learn from each of you.
As always comments and criticism is welcome.
Dave