Ixnay on the eamerray. Can jam, break, and just not fit. If the cake is too much, gently use a boning knife. My hands shake, yet I did a better job than the reamer I bought
In the 40+ years I've been smoking and maintaining pipes, I've had this happen exactly zero times. The only issue I experienced was when I bought a Castleford reamer set and gouged the wall of a pipe because the reamer blade hadn't been finished off properly and there was a bit of excess steel burr left on it that I missed. That's why I don't use cheap crappy Chinese knockoffs of the Pipnet, which is what the Castleford is. But you have to have the correct tool for the job and you need to know how to use it. Besides the Pipnet I also have Buttner, Swedish steel reamers, and other tools. And unlike some Youtube videos I've seen, you don't just jam them in and twist. You cut your way in and you do it carefully.
I can use a knife, but as a collector of fine vintage Britwood, I've seen dozens of pipes scarred by troglodytes wielding pipe knives, gouged walls and rippling rims.
If Carnuba and a buffer is a problem, you can use either Paragon or Halcyon paste waxes to achieve a brilliant shine without the need of a buffer.