In my humble experience, the Weatherby ultralight weights really suck!!!! I've had many Weatherbys over the years but generally find accuracy less than I would like to see in a premium off the shelf rifle.

The most aggregiuos case was a Weatherby varmintmaster in 7mm-08 with the factory Krieger Criterion barrel.
What I did to turn it in to an absolutely incredible tack driver was to free float the barrel. I carefully and meticulously used my Dremel tool to remove the two raised lumps inside the tip of the forend that Weatherby uses to add forend pressure to the barrel. Next, I rebedded the action by using epoxy at the action to stock contact point to raise the height of the front of the action to add a slight tilt to the barrel to ensure clearance from the stock forend. It is somewhat sacrilegious to rebed a rifle already equipped with an aluminum bedding block, but it is every bit as sacrilegious forvWeatherby to ruin an otherwise wonderful rifle by building rifles with forend pressure on the barrel and screwing up what could otherwise be a great AND accurate rifle. After my surgical procedure was complete, this rifle was a fantastic shooter and I kept it until I wore out the barrel after several thousand rounds shooting 1000 yard F class matches.

Funny enough, about two years after I did this, Weatherby announced their free floated Accumark lineup. Lo and behold, they free float those barrels, contrary to their traditional practice of using forend pressure.

Now, after that long winded rendition of my Weatherby tinkering, I shall get to the point of this post: I have had two Ultralights, both in .257 Weatherby, and tried the free float magic on both with disasterous results. Both rifles went from a ~1+ MOA rifle to one barely capable of throwing loose shotgun patterns. So, fortunately, before using epoxy, I would use a shim under the front action lug, just to be sure of the results I'd achieve, so it was relatively simple to turn them both back into a forend pressure rifle. Interestingly enough, what I've also discovered, was that both rifles were very respectable shooters when shooting from a cold barrel. One shot on the target, then wait a half hour, then shoot again one shot, and the rifles were sub MOA. Heaven help me if for the second shot there was any barrel heat, as the warmer the barrel got from the time the first shot was taken, groups opened up. I suspect that whippy noodle thin barrel is the cause of my consternation.

I now have pared down my Weatherby stash to 3: A .340 Accumark, a .458 Lott DG, and a .257 Ultramark. The Accumark is very accurate, easily sub MOA, with the DG and Ultramark around the 1" level of accuracy. I didn't try the free float on either the DG or the Ultramark. The accuracy level is sufficient for hunting, so I've left 'em both unmolested.