What inline has the powder positioned directly under the primer?

I should have said "directly inline with the flame channel of the breechplug"

It might work, but I think you will have some misfires. Unless the granules move in good amounts into the sidelock channel, it won't ignite. Sometimes I have trouble getting pyrodex or 777 granules to make that turn, especially after a shot or two. I believe you will have trouble getting the BH granules even more so.

Just because they told you it was safe, doesn't mean it will go boom. Be sure and let us know how that works out.