[Steinar]

Chris, I'm sorry to hear about your father having mild dementria.

I have been trough the same as you might be going trough. Ever since, I have payed a little extra attention whenever there is new information about threatment/medications. There is not much that helps, but as I understand, there is a newly developed medication called Ebixa, in adition to the most common Aricept, Exelon and Reminyl. If and how they work, I don't know. It might be something worth taking up with his doctor next time, as early as possible.
(They are not ment to make the patients better, but can help reduce/stop the 'acetylkolinesterase' in the brain.)
As to the guns, this can be touchy subject, and I think the best to judge is yourself. There are many things to consider, dementria can sometimes lead to the person becoming depressed, esecially on an early stage. To have something familiar to hold and talk about can reduce this (like fondeling with a EMPTY gun). Shooting at the range could also be a positive experience.
Later, IF things go for the worse and reality gets twisted, I think it's important that the guns is taken away and not used. 'Things' might change within a second if badly affected.
Can't give any better reply to you Chris.. I don't know much 'medical' things around the subject, but if there is some way I could help you, I'm glad to do so.
Wish you and your dad all the best.