Check one or both of the bearings are not crooked in the shell. They should be pushed up flat against the circlip ring that's behind the bearing.

It should go in. Apply a generous amount of grease to the spindle and bearing surfaces. Then if it's still a tight fit use a soft hammer to gently tap it in.

All BB30 bearings are the same size 42x30x7mm regardless of brand. The Sram bearings are no different to any other.