I would look at using Hodgdon Long Shot powder. Slow burning, low pressure and can produce very high velocities although I would stick with slower speeds.  It burns as you mention and like 7625 it provides a louder boom with the same loads using other powders.
		 
		
		
		
		
		
		
			
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				Progress is the mortal enemy of the Outdoorsman.
			 
		
		
		
		
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