Garry, Right around 8000 psi. It very hard to get pressures much lower than that and get a complete burn. Remember the smaller the bore the higher the pressure. This load I gave you is a joy to shoot.

Dave,

Many thanks! I've order the wads and will give this load a try. I appreciate your time in helping me.

Gary I shoot a similar load in my 16's both fluid steel and Damascus with no problem. SR 7625 has been discontinued but if it changes to Unique be sure to work up gradually as the two powders might have different burn rates.

Dave & Dean thanks for the choke info. In all honesty I was just giving Dave a hard time because I thought he was having a senior moment with his grammar:) It's good to learn something new thanks:bowdown:

Rich,

Thanks! I have some SR 7625, so I'm good for the near future. I don't quite understand the comment "if it changes to Unique." Sorry to be slow-witted (I know I am, my wife tells me all the time!). Are you saying that I might substitute Unique for the 7625, or is the manufacturer suggesting this...or whoever developed the load is suggesting it? I don't have the capability to monitor pressures, so I'm a bit confused about this.

In Dave's post he mentioned using SR7625 but that it was changing to Unique as 7625 has been discontinued. When substituting powders even though one supposedly replaces another it's best to work up gradually.

Gotcha! Thanks for clarifying.

Interesting comments on powder burn rates:

http://www.chuckhawks.com/powder_burn_rate.htm

Why Powder Burn Rate Is Meaningless By Randy Wakeman

Perhaps you have looked at various "Burn Rate Charts" and wondered what good they are. Well, you have good reason to wonder. Burn rate charts seldom agree. There is no specific meaning for "burn rate," so it shouldn't surprise us that the numbers don't agree. They mean nothing by themselves.

What amateurs call burn rate is not used by professional ballisticians to develop loads. The actual term closest to burn rate used in interior ballistics is "Relative Quickness."

Relative quickness is defined by "closed bomb tests," which quantify pressure rise in a sealed container. However, professional ballisticians do not use relative quickness for load development, either. A closed bomb relative quickness value does not translate into any type of value outside of that 'closed bomb' test. Powder performance varies widely by actual application. Relative quickness is one of several preliminary considerations when assessing a powder's suitability for a particular application by ballistics, but nothing more than that.

Relative quickness does not tell use the physical shape of a powder, its composition, or the types of coatings. It cannot tell us whether a powder is single-based, double based, or triple based. It does not tell us the heat of explosion, the progressive / degressive gas creation values, the ignition characteristics, and so forth. There is no way to translate a double-based powder performance into a single-based powder performance level with any accuracy. Even further, relative quickness does not define the erosiveness of a powder, the residue left by a powder, its ability to meter properly; and on it goes.

Energy content of nitrocellulose varies by manufacturer. It varies by the amount of nitrogen in the nitrocellulose. The more nitrogen, the more gas a powder can make. Once you have a specific type of nitrocellulose the energy content is further controlled by the addition of nitroglycerin, which is basically what constitutes a double-based powder. Now you have further considerations, as nitrocellulose and nitroglycerin do not behave the same way as temperature changes. The amount of nitro percentage varies by powder to powder, and with it its performance in a specific application.

All this combines to make burn rate charts something to ignore, or to view with very little importance placed on them. Professional ballisticians do not use them at all, simply because they have no particular meaning. Ping-Pong balls are nitrocellulose, but not many of us would bother cutting them up and attempting to use them in a firearm.

The "go ahead and open the chokes, it's your gun", versus the "keep it original" argument is surely a never-ending debate. But, I enjoy following it wherever it leads. The battle lines may be irreconcilable, but that does not prevent me from learning something new each time the topic is brought up.

This may stir things further: Spreader loads can compensate for all the older, tightly-choked Parker guns, but, admittedly only minimally -- given that the shot charge of a modified-equivalent may not be open enough for the grouse woods. But, once you open the chokes, is there any going back? Do you shift to "constrictor" loads, after opening up your factory-choked gun, if later in life you get a chance to hunt the broad expanses of the American West for upland game where longer shots are the norm?

REC

That's an intriguing concept - "constrictor" loads. Is there such a load available, or a 'component' that will allow us to load our own?





.

This is an easy one...get another gun!! (And now you have another good excuse).