Join the 16 ga Society's pressure group. Here's the link: http://www.16ga.com/forum/viewtopic.php?t=921

More low pressure loads than you can try in a lifetime.

It's the best $20 I ever spent on my 16 gauge. BTW my Joseph Lang was built in 1866 with replacement damascus barrels by James Woodward that date from 1872 or earlier. I've put over 2,650 cartridges through it in a little over 2 years - about 400 RST factory loads and 2,250 of my low pressure reloads. I only load 7/8th ounce in mine in deference to 144 year old wood.

I would never shoot SAAMI standard american factory loads in guns as old as ours. You might never have a problem but then again .......