Does Duplexing Steel Shot Impact Patterns?

 

Am I the only one who’s noticed that in the last few years, a sizable percentage of new movies are simply rehashes of older ones?  Mad Max, RoboCop, Top Gun,  Running Man…*  It isn’t just movies, but music and clothing too.  Is there no originality any more?   

Well, there certainly doesn’t seem to be in the shotshell world: witness the flurry of duplexed steel shot loads that are coming out.  Of course, duplexing steel shot sizes is an old idea.  In the late 1980’s, Remington marketed steel shotshells loaded with blends of shot sizes.**  The rational was, as stated in Remington’s brochure, Shooting Steel Shot with Confidence (1987):

“With new SP MultiRange Duplex™ shells, heavier shot is loaded in front of lighter shot to help you cover the entire range of 12 gauge possibilities. At closer ranges, the smaller shot size performs just as you'd expect, providing pattern density and uniformity, while the heavier shot increases your effective range. At longer ranges, the larger shot size supplements the pattern density of the smaller shot and provides high energy for penetration and knock-down power.” 

They even included a fancy picture to help explain.

Though, on closer inspection, it appears to be an add for some kind of multi-choke system…

Not to be outdone, a couple years later, Federal released shells with three different shot sizes. 

Both were dropped within a few years.

Just like a trailer for Saving Private Ryan II, the latest round of innovation doesn’t sound that innovative. 

Winchester Final Pass: “Features a unique mix of precision-plated steel shot sizes to deliver maximum pattern density and pellet energy upon impact”.***

Federal Ultra Steel: “Available in… double-stack loads that feature two sizes of shot: smaller pellets that create full patterns and larger ones that deliver better lethality at a distance.”

Remington Nitro Steel Duplex: “Blended, high velocity magnum steel payload gives dense patterns with the smaller shot size close up, while the larger shot hits hard close and maintains energy at longer ranges.”

Kent Fasteel+: “Each Fasteel+ shell incorporates a unique layered shot configuration, containing two different shot sizes in a single payload. For example, our 2x4 loads feature a layer of No. 2 shot over an equal amount of No. 4 shot, allowing the smaller shot to draft behind the larger pellets for tighter patterns and improved terminal performance. This innovative design ensures better penetration, enhanced pellet distribution, and increased knockdown power at longer distances.”

Migra Stacked Steel: “…whether you’re targeting ducks, geese, or other waterfowl. Combining multiple shot sizes in one load, the Migra Stack Load provides an edge in the field by increasing versatility across different hunting situations.”

Unfortunately, once you start doing the math, The idea of having a more effective all-around shotshell, since it contains long-range and short-range pellets or a goose-sized and a duck-sized pellets, just doesn’t pencil out until you get up to 12 gauge 3.5” or 10 gauge loadings.†

But, as seen in Kent’s blurb, there’s another claimed advantage to duplexed shot sizes; namely, that inclusion of larger shot will impact the patterning of the smaller shot.  According to this belief, when larger shot is loaded on top of smaller shot, the smaller will draft behind the larger and pattern tighter.††  Conversely, if the large and small shot are reversed, the larger will spread out the smaller producing a wider pattern.‡  In both cases, the load is thought of as a load of smaller shot with the larger providing pattern manipulation.

The questions are:

1)        Does combining different shot sizes actually effect patterns?

2)        If so, s it actually an advantage over the same shot charge of just the smaller size?

To answer these questions, I thought I make some holes in paper.  I make no claims to scientific integrity—this is a back yard, hey-y’all-watch-this kind of test.  I only shot one pattern of each of the following combinations.  It was getting windy, making it hard to get the paper to stay on the board.  Also, I had been shooting for a while and my shoulder was tired.  (I’ll finish shooting some more later and update the numbers if needed.)  But even if it’s shoddy testing, it’s a heck lot more useful data than this from Remington:

      

 

I chose a pretty standard duck load using #4 shot.  I wanted a load that would actually be useful (for someone anyway) but didn’t use up too much hard-to-find powder.  Also, I have a lot of #4 shot, which I hate.  

As controls, I loaded 1.125 oz of #4 shot (for the whole shot charge) and 1 oz of #4 shot (for the pellet count.

The duplexed shot charges we set up to provide the same pellet count as an ounce of #4 shot, which comes out to .875 oz of #4 and .25 oz of #1.

               #4: 438 g = 192; 383 g = 168

               #1: 438 g = 103; 109 g = 26

I loaded large shot on top and large on the bottom to test the tightening/spreading theory.  I also tried large and small blended and large and small stacked just for the fun of it. 

12 ga 2.75” Rio
Rio G-1000
32 g A.Steel
LBC43 + felt as needed
492 g steel shot
        A: 492 g #4 (216 pellets).  Control #1
        B: 438 g #4 (192 pellets). Control #2‡‡
        C: 109 g #1 under 383 g #4 (26 + 168 = 194 pellets)
        D: 383 g #4 mixed with 109 g #1 (26 + 168 = 194 pellets)
        E: 383 g #4 under 109 g #1 (26 + 168 = 194 pellets)
        F: 194 pellets stacked thus:
               9 pellets #1
               84 pellets #4
               9 pellets #1
               84 pellets #4
               9 pellets #1
I don't include velocity or pressure values because I don't know them.  It is, as far as I know, an un-tested load.  I am not recommending it.  

 

Patterned through a Remington Express with a Rem. flush IC choke at 40 yards. 

Load:	Shot in 30” circle	Total shot on paper
A: shot weight control	133 / 216 = 61.6%	183
B:: shot count control	111 / 192 = 57.8%	166
C: #4’s on top	116 / 194 = 59.8%	177
D: #4 and #1 mixed	96 / 194 = 49.5%	170
E: #1’s on top	146 / 194 = 75.3%	180
F: shot stacked	124 / 194 = 63.9%	170

 

Of course, if I shot multiple patterns with each shell, it might change the numbers significantly.  But taken as it is, it does still point in some directions. 

Of the pair of loads of straight #4's, the heavier charge (A) obviously prints better than the lighter (B).  

1-1/8 oz #4's

1 oz #4's

Interestingly, as a spreader, large shot on the bottom (C) doesn’t seem to work, which roughly equals the pellet count control (B).  Far better as a spreader is the blended shot charge (D).

7/8 oz #4's on top of 1/4 oz #1's

7/8 oz #4's and 1/4 oz #1's mixed

For tightening the pattern, large shot on top (E) does indeed appear to work.  Not only did that load beat both controls in pattern percentage, but more importantly, in pattern pellet count too.  

1/4 oz #1's on top of 7/8 oz #4's

The stacked charge (F) is interesting: it seems to have balanced the tightening and spreading effect to create a neutral pattern.  Kind of like the sneakers with tuxedo look.  The ridiculous amount of fiddling required in loading makes the sicko in me want to recommend it. 

7/8 oz #4's and 1/4 oz #1's stacked

The question then arises, why not just control the pattern with choke constriction?  I suppose, if you had two loads you wanted to use through the same choke, and wanted to even out the performance?  Say, if the choke likes a goose load, but not the duck load, duplexing the duck load might be a way to bring it into line with the other?  Of course, you could most likely find another non-duplexed duck load that would work. 

 UPDATE 7/25/25:

The test of the variations on the #4 load above are just one data point.  They don't prove anything except that that particular choke likes load E, and therefor, that we can't say duplexes never tighten patterns.  But the test doesn't prove that duplexes always tighten patterns.  I'd have to test more loads to decide that.     

While rummaging though a box of old patterns last night, I came across some of a duplexed load I'd tried a few years ago and had forgotten about.  At the time, I was working on another project and had thrown in a duplex just to see what would happen.  My results were mixed and generally unimpressive from a practical hunting standpoint.  But they do illustrate the fact that we don't have a Law yet.

12 ga 3" Remington .25" basewad
Win 209
35 g Alliant Steel
NTC 3"
495 g steel shot
    G. 53 x #BBB under 10 x #F (63 pellets total)
    H. 68 x #BBB

Patterned through a Remington Express  at 50 yards through these chokes:

   Carlson’s extended Light Modified (.714”)
   Carlson’s extended Improved Modified (.704”)
   Hasting's extended Steel Shot Full (.706” actually an IM) 

	G. #F x #BBB	H. shot weight control
Carlson’s extended IM	35 / 63 = 55.5%	52 / 68 = 76.5%
Carlson’s extended LM	45 / 63 = 71.4%	54 / 68 = 79.4%
Hasting’s Steel Shot Full	47 / 63 = 74.6%	46 / 68 = 67.6%

Here we see that the duplex was not improving patterns with the LM or IM chokes--in fact they're degraded in percentage as well as pellet count.  However, the duplexed load performs better with the third choke in both percentage and pellet count--it's only 1 more, but still, that's more (cf. This Is Spinal Tap).  Again, we can't say "never" or "always" with duplexes.  To Kent's claims at the top of the post, all we say is, "ok, maybe."

But we can also say duplexing is a handloader's tool that might solve a particular problem.  Generally, I chose a load and find a choke that works for it.  But what if I can't switch chokes?  Of those six combos, I'd pick the straight #BBB with the Carlson's IM; but if I had the Hasting's choke stuck in that gun, the duplex would be a better choice than the one-size load.  Imagine I have a fixed choke gun that I want to shoot #3's with, but I can't get the pattern I want from them.  I could try duplexing the shot, and it might help.  

---

* Part of me hopes for Titanic II.

** Remington also duplex lead shot in the 1980’s.  I don’t know if they or anyone else had done it earlier.  I find it hard to believe they were the first.

*** As well as, interestingly, “Half-sized shot improves pellet counts without sacrificing critical penetration”

† Let’s look at a #BB x #2 combo.  #BB steel = 72 pellets/oz.  #2 steel = 125 pellets/oz.  Since what will kill a goose will kill a duck, we’ll start with the goose portion of the load.  According to CONSEP, we need at least 50 pellets in the pattern for a goose.  So, assuming a 75% pattern, we’d need .93 oz of #BB in the shell.  Again, CONCEP stipulates 85 pellets for a mallard, which with the #BB’s already there, means at least 35 #2’s in the pattern.   Assuming the same 75%, we need .376 oz of #2’s in the shell.  That means a load with 1.305 oz of shot would provide the bare minimum for geese and large ducks with NO margins for error.  We need those margins obviously, so prudence would guide us to 1.375 or 1.5 oz of shot.

† This itself is based on the widely held belief that larger shot patternstighter than smaller shot.

‡ I’ve never gotten a clear answer on why this would happen.  Perhaps because the larger shot retains more velocity and pushes through the slowing down smaller? 

‡‡ This perhaps isn’t a fair comparison, since the lighter shot charge will lead to a higher muzzle velocity, which touches on another piece of received wisdom, viz. that slower shot patterns better.