I have a Bushnell 2-6 Trophy also. After about a dozen shots while sitting on a Colt Anaconda .44 Mag it would not adjust. Sent in to Bushnell under warranty where they replaced the power ring, seal, and gasket. The paperwork did not say what had gone wrong with it. I never did put it back on, maybe someday, but the Anaconda shoots better without it.
I would go with a scope dedicated to handguns over a rifle scope. They have a longer eye relief than rifle scopes. If you were to go with a rifle scope look for one that would be ideal for a scout type set up, they also have the longer eye relief. Leupold makes a nice 2.5-8 handgun scope that looks like it would work well except for the price tag.