That’s excellent work and analysis. I bet you put the steel shot on the bottom and it patterns perfectly. As it is, your core is great. Now just let the faster slowing steel shot fill in the holes. Very nice!!Here is some initial data from my duplex load tests.
This load is courtesy of CMwings who developed and tested it. These components fit together perfectly.
Load test report from CMwings: 1400 fps, 9000 psi
- 12 ga Cheddite 2-3/4” 8mm brass, new, primed, skived
- 29 grains Longshot
- TPS 12ga 35mm wad
- X12X Symmetrical Gas Seal
- 3/4 oz Zinc-Plated Steel Shot #3
- 1/2 oz TSS #9
- 12 ga overshot card
- roll crimp
First, I trimmed 1/8" off the hull. Next, I hand loaded all components, weighing powder and shot for each load. I counted 5 samples of steel shot and 4 samples of TSS for pellet count.
Average count total pellet count 303 sample 1 sample 2 sample 3 sample 4 sample 5 steel pellet count 112 112 113 110 112 112 tungsten pellet count 191 189 191 191 192
TSS was loaded first then steel. After filling the wad with shot, I compacted the load with 40-50 lbs of force from a wooden dowel, and then placed the overshot card. I made the roll crimps with a precision reloading roll crimp tool and a hand drill. After crimping, a few pieces of steel shot in each load were about ½ diameter above the top of the wad.
8 patterns were shot on a 4’x4’ sheet of OSB covered with 48” wide white paper.
All patterns were shot at 40 yds from a bench rest to minimize human error in POI.
The weather was 55 F with a light breeze (<5 mph) in the direction of the shot.
All wads and spent hulls were retrieved (more on that to come).
Patterns were photographed and processed with the “Shotgun Insight” software by AC Jones. This software detects pellet marks in the photos and automatically calculates all pattern statistics. It was not designed for duplex shells so I added duplex statistics manually. The program output calculates the center-of-mass of the pellet distribution and uses that as the point-of-impact (POI) for the shot cloud eliminating human error in the placement of POI. It overlays circles at 10”, 20” and 30” centered on the POI to calculate statistics. The pattern images shown below from the program output show the point-of-aim (POA) as the center of the green reticle. The POI, the 20” circle and the 30” circle are also drawn in the output image.
Pattern minimum success criteria:
These criteria are based on characteristics I observe in lead #5 shell patterns I have been using for chukar hunting for 30 years.
Here is a 40 yd pattern from the lead #5 shells I shoot chukar hunting. This has a high probability of killing a chukar almost anywhere inside the 30” circle.
- Total pellets in 30” circle around POI > 170
- Total pellets in 20”-30” annulus around POI > 70 (This is to rule out high percentage patterns with a hot core inside a 20” circle. For example, a full choke pattern)
View attachment 381744
Lead #5 shell pattern statistics:
Pellets in 30” circle = 186
Pellets in 20”-30” annulus = 76
Finally, here is data for one of the patterns from the duplex loads that I have analyzed thus far and came fairly close to meeting my pattern requirements:
Duplex pattern #2 (modified choke):
View attachment 381745
View attachment 381746
Note: the "shotgun insight" image does not show all of the pattern board.
Steel pellets on the board = 85 (76% of total steel)
Tungsten pellets on the board = 170 (89% of total tungsten)
Steel pellets in 30” circle = 34 (30% of total steel)
Tungsten pellets in 30” circle = 154 (81% of total tungsten)
Total pellets in 30” circle = 188 (62% of total pellets)
Total pellets in 20”-30” annulus = 56 (18% of total pellets)
Comments on duplex pattern #2:
This pattern has a very dense core of tungsten shot combined with a blown steel shot pattern. The steel shot does not contribute much to the pellet count in a 30” circle around POI. It has an adequate total pellet count inside the 30” circle, but lacks pattern density in the outer 20"-30” annulus. Even though it meets the definition of a modified-choke pattern (“60% of total pellets in a 30” circle”), it has a visibly different density distribution with a more dense core than the lead #5 modified choke pattern discussed earlier.
I will continue to post more data as I can get it analyzed and written-up.