switching to TSS - 3 questions from a neophyte

[C M Wings]

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 recipe:

• 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

Load test report from CMwings: 1400 fps, 9000 psi

Loading procedure:

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.

Patterning procedure:

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.

• 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)

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.

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.

Pattern statistics:

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.

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!!

 

[C M Wings]

Your results may improve if you used steel or even LilGun powder. Longshot is a decent option, but in my experience through many gauges, shot types, and payloads, tends to throw varied patterns, I’m assuming it’s has to do with an aggressive pressure spike. All in all, you patterns seem workable and fine to me.

Apex used load or offer a 0.25 and a 0.50 #9tss load option over #2steel shot (1.25oz total payload) in a 3” hull. That held a tight core of tss and what you’d expect in a #2steel pattern in a mod choke at 40yards.

I’ve had varied patterns with certain shot sizes paired. Hw15 6’s and steel 4’s, for what ever reason have patterned better for me than hw15 7’s and steel 3’s. Both loads however kill geese.

You’ll need 32-33 gns of steel powder to match the speed here. That’ll be taller but will roll crimp in a 2-3/4 hull.

 

[C M Wings]

Did you recover any of the wads? Would like to see the setback you had.

 

[duckrogers]

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!!

I have a lot more data to post and some of it is just, well, weird. Nevertheless, I like the idea of putting the TSS on top because if I could fix the blown steel pattern and overlay a 70% TSS pattern I would just about have what I need.

This shotshell engineering stuff is kinda fun, but hard and VERY time consuming!

 

[duckrogers]

Did you recover any of the wads? Would like to see the setback you had.

Yes. This is where things start to get a little weird.

The TSS in the photo is embedded in the plastic at the bottom of 6 out of the 8 wads. Clearly this is where some of the TSS missing from the pattern board went. This concerns me because I have only seen this happen with one other shell: A Kent bismuth shell that I posted about here Kent post several years ago. That shell gave erratic patterns and some of the wads blasted clean through my 1/2" particle board. The duplex load wads landed 35-45yds from the gun, but I am worried that shot embedded in the wad interferes with the separation of the wad and shot charge after exiting the barrel and the wad perturbs the flight of the main shot charge.

Also, note that the skirt at the base of the TPS wads is compressed unevenly by the gas seal. I'm not sure if that affects the patterns.

 

[cd2]

I'm not sure what the pressure actually is on that load to be making the base of the TPS wads look like that. CM Wings, have you ever actually pressure tested that load with 29 grains of longshot? Try it at 33-34 grains of steel in a 3" hull.....ditch the longshot

My testing with 28 grains of longshot and an overall load weight of 1-1/4 oz in 3" 12ga with a shorter shot column that what you have was at 15,290 PSI. I'd bet with that load and 29 grains of longshot you are pushing 16,000 PSI. Maybe less with the roll crimp, but who knows. I would bet over pressure

If your pattern problem is that the core of TSS is too tight and the steel is just dotted around, putting the TSS on top will just make this worse. Your best bet is to loosen the choke to create a more even steel pattern and expand the TSS core. Have you shot an Improved Cylinder?

The pellets in the base of the wad are too be expected with initial setback and no felt filler in the wad.

If I were you I would only load pressure tested data with the exact load you are looking for and I would shoot an Improved Cylinder choke.

Try this:
3" Cheddite Hull
35 grains Steel
X12X Gas Seal
TPS 35mm
273 gn TSS UNDER 273 gn Steel
Fold Crimp
1459 FPS, 11034 PSI

 

[duckrogers]

I'm not sure what the pressure actually is on that load to be making the base of the TPS wads look like that. CM Wings, have you ever actually pressure tested that load with 29 grains of longshot? Try it at 33-34 grains of steel in a 3" hull.....ditch the longshot

My testing with 28 grains of longshot and an overall load weight of 1-1/4 oz in 3" 12ga with a shorter shot column that what you have was at 15,290 PSI. I'd bet with that load and 29 grains of longshot you are pushing 16,000 PSI. Maybe less with the roll crimp, but who knows. I would bet over pressure

If your pattern problem is that the core of TSS is too tight and the steel is just dotted around, putting the TSS on top will just make this worse. Your best bet is to loosen the choke to create a more even steel pattern and expand the TSS core. Have you shot an Improved Cylinder?

The pellets in the base of the wad are too be expected with initial setback and no felt filler in the wad.

If I were you I would only load pressure tested data with the exact load you are looking for and I would shoot an Improved Cylinder choke.

Try this:
3" Cheddite Hull
35 grains Steel
X12X Gas Seal
TPS 35mm
273 gn TSS UNDER 273 gn Steel
Fold Crimp
1459 FPS, 11034 PSI

Hmmm, that is worrisome. I thought I was using CMwings' pressure tested load. He reported:

Use a7/8 wad and 32 gns of steel or 29 gns of Longshot. Load whatever duplex you want with 1/2 ounce of TSS in a straight walled hull and a cheddite primer. 9K, 1350-1400 FPS. If you use a 1 ounce wad put 1/4 cork or felt in the bottom.

Reviewing your "ultimate load 12GA Waterfowl load" thread, your longshot load that failed the pressure test was:

3” cheddite hull
28 grains longshot
TUPRW123 wad
2 x 1/4” 20ga felt
273 gn tss under 273 gn steel
20ga OSC
fold crimp
1407 FPS, 15290 PSI

Is that correct?


CMwings can you weigh in here?

 

[C M Wings]

I tested 500 gns @ 34gns of Longshot. Shorter shot column for sure, but all I see in those wads is the gas seal going cockeyed against the wad. The gas seals themselves look fine. If it were over pressure you’d see the seals cracked, they are designed to fail like that, for that. Now, you might say yeah but at 3.5 inch gun pressure. That I don’t know, but these don’t show sign to me of being hot. They look like they got some typical blow by. But OP could always back off the shot column and add felt. That would def drop pressure. I agree steel powder is a better option. I used ls because I couldn’t find steel. Also why I tested this and another at 437/38 which came back 1600@11k.

 

[C M Wings]

The one thing I will say is that when I said 1/2 TSS and any duplex you want I assumed you were gonna load 1 ounce total.

 

[C M Wings]

I don’t see 29 Longshot having more pressure than 35 steel, especially in a roll crimp, but it def has a different burn rate. Op could back it off a grain or so. But I agree steel powder is a better overall option for taller shot columns.