w - Shotgun pressures have been reasonably uniform in the 7000-10,000 range for a long time (say, since the invention of guns). BP is not the key to low pressure loads. Modern USA loads to SAAMI standards are allowed to go higher. CIP (most of the rest of the world) are closer to the range cited. The trick is to figure out what pressures are suitable for your gun and use loads that meet that pressure.
Have your gun checked out by a knowledgable gunsmith - preferably one used to working with doubles, say Kirk Merrington in Kerrville (having noted ou are in TX). If it checks out, you will be able to shoot nitro loads of appropriate pressure, your loads to known pressure or selected factory loads.
