Do you believe that a 25 psi pressure difference has any real world significance ? Wouldn't you agree that 25psi is about the same as normal variations in powder measures anyway ?

Pressure
 

Bruce: "Wouldn't you agree that 25psi is about the same as normal variations..." I think Perry Mason would object because you are "leading the witness" :nono:. Best to all, Bob:)

Well when you are talking pressures of 6000 to 9000 depending on powder type 25 psi is a non issue , at least to me. That is less than BB gun pressure.

For the sake of those who may not have read and/or digested the Bell/Armbrust tests in Double Gun Journal, that aspect of their results is precisely the issue: It is insignificant.

In other words: Shooting low pressure/low velocity 2 3/4" skivved case cartridges in a 2 1/2" or 2 9/16" chamber does not raise pressures significantly. It is, indeed, a "non issue."

So, to be even more clear on the matter, this good fellow and his Parker are on safe ground. Assuming the barrels themselves have been checked and are found safe to shoot.

Finis.

Low Pressure/low velocity is an opinion recommendation and is not based in the Parker documents. Some Parker listed loads are pretty stout, stouter than I care to shoot on any frequent basis.

For example, almost all the Parker 12ga's were patterned with a 1 1/8 oz 3 dre load, which provides about a 1200 fps speed. That is a standard loading for pattern efficiency/distance and lead. Patterning tags provide this information. Heavier loads are listed in other Parker sources as are mean maximum working pressures in psi, which became the SAAMI standards when the Small Arms and Ammunition Manufacturers Institute was formed. Parker maximum loads were SAAMI maximum loads.

While shooting less than maximum loads makes much sense, it is not a requirement for a Parker in good condition. Parkers are not delicate and were not designed to underperform.