having extration problems with 458 lott brass in a Ruger no. 1 with Bell brass only . Hornady is ok. all other components are same. no other pressure signs.weighs of brass Hor. 245.5 grs. Bell 266.6 . heavy brass ,smaller volume,higher pressure ? Dimensions I checked were same. any ideas?

Case capacity is a factor in loading, You cannot always use the same load in brass of different lots, let alone brands.

You'll have to back off the loads using Bell brass and work back up.

What velocities are you getting with the two different cases? Do the Bell cases give higher velocities?

George