The flat surface goes on first onto the muzzle tube, the shortest of the three.
The other 2 are the same.
Ensure that the last one has the countersunk facing downward for the screw to fit into.
When tightened up they will be a small amount of play about 1.5 mm between the rollers.
Use super glue to lock it in place but don't put too much on as it will seize the bearings up if it runs off the threads.
When you've done it spray some WD or V 90 onto it to free it off, just in case.
Let your shooting do the talking.
It's not the aim and release that decided the shot, it's the preparations.