Spotting scope window mount

[TimberPig]

I have a window mount made by Simmons which has a standard 1/4" screw and a wing nut that is supposed to secure the scope to the mount. I've had a couple of these types and can never seem to get them good and tight to the scope, but when I mount the scope on a decent tripod everything gets rock solid. I use the scope mostly from the truck and its worthless if you can't get the scope mounted tight.

Does anyone have a recommendation for a good window mount that will handle large/heavy 80mm spotting scopes?

 

[CamoMan]

I have a Burris 15-45 spotting scope, and I have been using the Nikon windown mount. I really like it because it has a base that fastens to the spotting scope, then it can be fit into the window mount and locked in. This is handy if you want to quick-release it, and move on down the road without removing the window mount. It fastens in tight, and the window mount secures to the window very easily. They have them at Sportsman's - one of he best presents my kids have given me.

 

[TimberPig]

I have looked at the Nikon mount in magazines but not in person. They look pretty sturdy. I dont think they have the wing nut on the bottom? I think thats where the trouble comes from.
I can get a smaller scope reasonably tight, but a heavier longer scope adds alot of leverage to the mount and it doesnt take much wind or truck movement and its all over the place. The scope I have is a Pentax PF-80ED, about 20" long and it weighs about 70oz. The optics are great but it is definately a tank.