Ball seal calcualtions

[CyDyne]

I'm looking for a formula or reference on how to calculate the amount of preloading a ball seal would need to withstand a large amount for pressure.

I want to use a 3/8" bearing to seal a volume. the bearing is held in place by a 7/16" hollow set screw. See the picture.

I can calculate the preloading of the ball. I'm having a hard time on modeling stresses.

is the situation like this or:
(a) (b)
____________ _____________
< < < <
> > > >
Ball < Ball BODY
> > > >
< < < <
_____ BODY ______________
▲ < ▲
| > |
P < P
| >
▼ <
____________

I think it is more like (a)

but I don't know how to put that into an equation that.