I think folks get overly caddied away with "Low Pressure". Think in terms of the shot load & velocity you want the old gun's wood etc to stand up to. You use that slow powder to get real ,ow chamber pressures vs a faster powder which gives the same load of shot the same velocity then at about the end of the chamber to the end of the forcing cones those pressure curves are going to swap places & from there on out the "Low Pressure" load becomes the "High Pressure" load. A gun that won't stand up to 7500-8000 PSI chamber pressure needs to be relegated strictly to Black Powder or preferably hung on the wall. I would much rather have a slightly higher pressure in the chamber where the walls are thickest than have a Squib out in the boonies or swamp.
If it is strictly a moderately warm to hot weather target load you can get away with a bit lower chamber pressures, but I Just Don't Trust those super low pressures with slow powders for hunting loads.
