Ken,

B&P makes only one 16 ga load that they import to to US and they are firecrackers as well as deadly... but they are nearly 9,900 psi. I love them on pheasants in my AYA but even then in the 2nd barrelo nly.

Here is their pressure chart:
http://carolans.com/R/bp-1/content/Speed-and-Pressure-Chart.pdf

That said, I have had great success with RST 16s in #6 copper/1 oz on SD roosters thru my vintage Cashmore. My MN kin folk are constantly amazed how I can fold 60 yard crossing roosters with that little "pop gun" while they are banging away with 1 3/8" of high velocity 4s in 12 ga autoloaders.

The answer is SHOOT THEM IN THE HEAD. Don't take tailpipe shots. When I walk to push a field I seldom shoot, saving my shooting for outside or end blocking. The Brits truly understood a thing or two about how to dispatch Mr. Phez!

Dr. P