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Do unlimbered cannon in a woods hex get the -40 % Protection that the hex shows i saw a post that says no but cannot find an answer in the rules

Yes, they do

What!? When did that change?

When Antietam v4.05.3 was rolled out (https://wargameds.com/blogs/news/civil-war-battles-4-03) we were told:
"Adjusted so that Artillery in forests/villages will not benefit form a defensive hex bonus versus ranged attacks if the attack is directed through a clear hex side."
That change was noted in the v4.05.3 Changelog.

When v4.05.4 (comprising v4.05.3 and some additional changes) was rolled out for all titles the v4.05.4 Changelog noted:
"Adjusted so that Artillery in forests/villages will not benefit form a defensive hex bonus versus ranged attacks if the attack is directed through a clear hex side."

There is nothing in subsequent versions listed in the Changelog to say that that change was ever undone. That's why in the discussion about the Artillery Thing (https://wargame.ch/board/acwgc/viewtopic.php?f=4&t=24077) there was no mention of using forest hexes to lessen gun casualties. Only things like breastworks, trenches, elevation and walls were noted.