SOunds like you have a winner. Factory ammo is no guarantee of reliability. Now go do some handloads & see what she'll do. For the 210grNP my rifle likes RL15 or IMR 4320.

I got my 1952 721 action back the other day. Had Shaw put on a 24" Remington Mag contour in 338-06. Topped with a 2-7x Nikon monarch. Took it to the range with a (expensive) box of weatherby factory ammo. Zeroed the rifle and then shot 4 , 3 shot groups. The smallest (center to center) was 0.31", the largest was 0.61". Not too bad.

Two weird things happened. First, there is a burr in the chamber, it leaves a mark on the brass, but does not seem to affect extraction at all.

Second, one of these $2+ per shot weatherby rounds misfired! After a few tense moments, I recovered the round from the chamber. The primer was dented, but not enough to cause ignition. So I immediately thought my 52 year old firing pin spring was getting weak. Not so, after closer inspection, it was clear that the primer had actually pushed deeper into the primer pocket, thus preventing the firing pin from properly impacting the primer.

So, there was an example of a misfire at an opportune time...