Calvin,
I have two 1881 lifter Parkers with Twist barrels as well. One is a 10 gauge and the other is a 12 with straight grip and 30" barrels like yours. I shoot mine with smokeless loads most of the time. Sherman Bell compiled a lot of data on black powder vs smokeless and found that in some cases the pressures are at the same level in the same locations. You could shoot shells from
www.rstshells.com as they are made for old guns like ours. If you want to reload smokeless loads I can give you some data.
Harry
Threaded Mode