USH scope rail adjustment screw

[sliceman]

I recently bought a 20 ga. USH expecting good accuracy as noted by many members of this board. The accuracy was terrible, despite 2 proven scopes and different mounts and various ammo( Fed Barnes expanders, Rem Core-lokts, Win part.gold). I saw a post here about the scope rail being loose, so I took the 2nd scope off( discovering in the process that 2 screws on one side of the Leupold PRW rings had broken) and checked the rail-all the 3 back screws were tight, but then noticed the front screw was not  attached to the barrel, but was a tensioning screw, lifting the front of the rail off the barrel a variable amount. My question is, how much tension shoud one put on this screw?
I think this will be the problem as accuracy was poor with the first scope and rings I used, and that setup was still tight when I tore it down. Suggestions?

[quickdtoo]

It's supposed to by .0015" off the barrel, it's there just for support of large scopes in case it gets bumped, this info is in the FAQs and help sticky along with a LOT more. 

Tim

[Busta]

You must have one of the old Ultra Scope Rails for rifles? Not needed on a shotgun, but since that is what I think you have, you don't want any tension on there. IIRC you want a .0015" gap, I believe it was put there to keep your rail from bending downward. I know it is cantilevered out there quite a ways, but that is what I remember (or think I remember) reading several years ago. It does have a brass standoff attatched to the end of the screw and two set screws to lock it in place.

They have discontinued this Ultra Rail, FWIW. There is probably something in the stickies about it.

Dang quick, ya beat me to it!