Welcome, Andrew! You haven't told us about your Brick. Does it have its original handlebar? Where did you get the grips that you are mounting?
When you buy a set of grips for a Brick, you buy a 22mm set because the BMW Brick handlebar tubing is 22mm in diameter. When you receive the set, the clutch lever-side grip will be 22mm in diameter; the throttle-side grip will be larger because it fits over the throttle tube which fits over the 22mm handlebar.
Often 22mm and 7/8" handlebars are advertised for sale as the same size; they are not. A 7/8" handlebar is 0.225mm greater in diameter than a 22mm bar. To use a 22mm grip on it, the bar end diameter needs to be reduced to fit it.