I chuck my steel broadhead adapters in a standard hand drill or drill press, while they are spinning, I use 100 grit sandpaper folded over and gently lay it against the spinning adapter.
Try to maintain the same taper, and it doesn't take much to get them to fit all of the way into the griz. ferrule.
Keep checking often, and only a few seconds at a time with the sandpaper should do it. I just did a half dozen yesterday, took about 15 minute.
When you get done, you'll have plenty of depth in the grooves of the adapter to hold the glue.
I then just clean out the broadhead ferrule with a wire bore brush and then a q-tip with acetone.
I then acetone the adapter and you are good to glue.
I thought about "reaming" out the ferrule to make them fit, but thought it may weaken it.
Hope this helps.
John