How old is that package? I couldn’t find anything on Speers website with a similar warning.

There’s a big difference between a compensator and a ported barrel. I could see the potential for a ported barrel to shave off small pieces, however there is no way this will hurt the barrel or porting. It might send small pieces of copper plating flying out but wearing eye protection will be sufficient protection.

If a bullet is exiting the barrel and hitting the compensator it’s because the compensator isn’t appropriately attached.