Gunnery/Sights question

[noxnoctum]

Thanks guys. I also dug this up from a simhq article:

http://www.darts-page.com/files/gunnery02.htm

Question though, are the 190, 109, tempest and P-51 main circles 20 degrees also or less? They look smaller, but maybe that's an optical illusion.

And the hash marks on the 190, are they 5 degrees each or 10?