1)
In the same patch where they removed wobble reduction for bows in tripods, they added reduction to towers. Would not make sense to include bow reduction in towers when they just removed it for another stand.
http://news.thehunter.com/game-update-95/
2)* Removed bows getting wobble reduction from tripods
* Stationary hunting towers in reserves now give wobble reduction
Here they explicitly mention guns when talking about wobble reduction in towers.
http://news.thehunter.com/status-update-271/
Gun Wobble in Towers. We are aware of this issue and believe we have found the issue, after we are happy that it has been fixed, you can expect it in a game update soon.