The topic of proper and safe loads for Parker and other American doubles is often discussed and not often agreed upon. The British do not have this problem for long ago they mandated that each and every gun be proofed for maximum service (normal use) pressure and load. This is stamped into the water table.
Parker being a good business found it prudent to advise users of their guns as to the proper loads. It would not have been good for business for their light guns to be shot lose by sportsmen using heavy loads. I did not find this in the Parker Story. It is an advertisement which I found on the Internet. It is hard to read due to its small format. If anyone can provide this or something similar in large format please add it to this thread.
Below is what I can best read in the add. The column of numbers was most hard and for the fractions I used 1/2"
“Suggestions to Persons Using the Parker Gun.
Parties using our guns are recommended to use Standard Wadding. Wads, larger that the shells are not necessary, always putting them down to place flat and square, otherwise the shooting qualities of the guns will be greatly impaired.
If Brass shells are used we suggest two size larger wads than gauge of gun. As a guide for charges of powder and shot to be used with the different gauge and weight guns, we submit the follow as a basis, which varies according to gauge, length of barrels and weight of gun, although “the distribution” can be increased either by decreasing the quantity of powder used, or increasing the quantity of shot. And to produce better “penetration” increase the quantity of powder used, or decrease the amount of shot.
It is on advantage to place a large charge of shot in a small bore, as it only increases the column of shot in depth, but not in width. The result of this is the shot get jammed and great friction is caused in passing out the barrel. If large quantities of shot are to be used, the proper way is to use a larger caliber of gun.
The exact amount of ammunition required to be used with each gun, to give the satisfactory results to parties owning the gun, can only be ascertained by repeated trials at the target.
Below we give a general formula for loading:
Gauge Weight Lbs Barrel Length Shot Oz Black Powder Drams"
----
I developed an Excel table but lack the knowledge of how to add it and not lose the formatting.
My opinion of this is to "Use enough gun"! If you want hunt Rough Grouse with a light gun then do so. If however you also desire to hunt tough, late season Pheasant you better get a bigger gun!
Mark