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I got a spreadsheet somewhere that features lower pressure loads in 12 gauge. I have used 4500 to 5500 PSI loads effectively at the range...with a damascus gun. No bloopers. One thing you might notice with lower pressure loads is that they sometimes become dirty. Leaving behind unburned powder.

Member Joined: 09 Sep 2014 Posts: 105 Location: Virginia

Want to confirm unburned powder push a dry paper patch through the bore. Look carefully at the residue. If the grains are perfect and uniform it's probably unburned powder. To be sure take the paper outside and light it with match on a clean spot, burns over to the grains unburned powder will fizz, no doubt about what it is.

Thats how I figured my 14 Gr load was too light, and why I went to 14.7.

Boats

Charlie, it might be best for you to first research the relative burning rates of smokeless powders suitable for use in shot shells. The following is based on my own experience w/ extruded flake powders which tend to be easier to ignite. Ball powders tend to require higher average peak pressures across the board to burn efficiently based on my limited experience w/ them.

As a rule of thumb, and assuming your load crimps are always well formed and firm, the faster the relative burning rate of a given smokeless powder, the lower you can go w/ the average peak pressures and still get acceptable results (and vice versa). Fast burning flake powders like Red Dot will usually burn okay at around 8K PSI peak pressures or higher. Slow burning flake powders like Blue Dot require a minimum APP of around 9.2K PSI or higher. Mid-range flake powders like Unique seem to do okay at 8.5K APP or higher. However, w/ few exceptions like my pet 3/4 oz. Green Dot loads (about 8.5K PSI APP), I've found my own loads seem to perform the best across the board if I keep my APP's up to 9K PSI or higher.

My experience w/ ball powders suitable for shot shells is limited. However, I've found acceptable burning efficiency seems to require about 9K PSI APP minimum and up for these harder to ignite powders. Others here might disagree based on more experience w/ ball powders. Perhaps they might weigh in here.

Joined: 28 Aug 2014 Posts: 924 Location: Eastern Tennessee

16gg,

Interesting, thank you.