I just did that this evening and messed up two buckings one of them the PDI bucking and the other the TM stock bucking.
Now after reading a bit on buckings I found out that the TM bucking is a good piece of plastic. So I am a bit disappointed.
So I will test the Firefly, G&P and PDI buckings all sanded down via dremel. (with bump and alinement sanded down)
I am going to wait for the firefly nub (flat) and then test out each one. Hopefully I will get a fix to my dilemma.
The w hopld bucking shouldn't be sanded iMo as it hits the bb in two places giving it better accuracy and stability. They are great. In my g36c I have a madnull sanded though which increased pthe range from 110ft to 160ft