ive done this often...its a good way since you can pack it in tighter than if you were to roll it...

what i do is..

empty out da black & mild by using tweezers or just rolling it in between both hands as if you were tryin to start a fire...

*dont cut it open*

stuff ur bud in the empty tube, using a pen or sumthing similar in size to pack in tha trees...then poof***you have yourself a slow burning blunt...