Hi Richard,
This observation doesn't address the Duplex / vs Straight Black question the you were looking for but my experience is that I've always done much better on targets with straight black vs. straight smokeless.
The couple of duplex loads I have shot clearly leaves a cleaner barrel.
I've not shot Duplex loads, other than a time or two, as I don't want to develop a load I couldn't shoot in comp. Not that I have been to a match or competed for the last 30 trips around the sun so it shouldn't matter but I prefer straight black
That being said my best results (single digit ES and lowest SD) come from the following
With Straight Black
30" Drop Tube
.12 compression
Swiss #4, (1/12F) all same lot number
Cases Full length sized
Fed GM 150 Pistol primers with newspaper disk over primer
Paul Mathews lube formula w/ cookie
Blow tube between shots
20/1
All fixed so far / no breech seating, (maybe future experimentation)
Grand slam wrote on Mar 27
th, 2024 at 9:15am:
Why are smokeless and duplex loads more accurate than black powder. Would like to know all of the pet theories.
Thanks Richard