If you want to see the obscene extremes one could go to in an effort to design the perfect BP, take a look at what the smokeless guys are doing. There is additional pressure there as the vent itself wears VERY quickly due to increased temps/pressure. It started with a removeable/replaceable ventliner, and has now progressed to improved flame channel designs, carbide inserts, primer carriers to get rid of 209s, etc etc. All of this outside the realm of the companies who made the originals.