I've seen some of that Finnish/Danish data. Some of it is pretty edgy. But I'm intrigued because VV powder is usually easier to find than A.Steel.
I feel like we're in a cul-de-sac with steel ammo right now. With alliant steel, we can easily achieve good enough performance in 20, 16, 12, and 10 gauges, and any push for better than good enough is channeled into HTL shot. How many other powders out there could do what steel does and more? Maybe none, but I dont think a lot of folks are looking.
Obviously, we're never going to turn steel into lead, but is 1.25 oz at 1450-1500 fps really as far as we can go?
This is merely a matter of curiosity on my part. One thing that annoys me to no end is the stick-in-the-mud mindset of so many shotgunners. Mention a 3" 16 ga hull and then find cover fast!
If only looking at the two, say Alliant Steel and Viht 3N38 (or 3N37), both are capable of the same performance and relative pressures of the same payloads. VV seems a bit more versatile with the 1-3/4oz and up loadings in the 10ga, but overall steel works well and is very useful for 10, 12, 16, and magnum 20 loads. I will say that in my experience Alliant Steel is the less efficient and dirtier burning of the two. Is it enough so to make a significant difference? I'm not able to really collect hard data on that, but anecdotally I would say it is enough of a difference for me. I still keep a couple pounds of it around though!
I completely understand the question of asking if the current decade old industry standards and "limits" of steel shot are really the pinnacle, and the answer is unfortunately "Yes". I have chased the white rabbit enough to find some very hard data that has proven to me the physical limits of the different shot types. Really, when launching steel (iron) shot, pushing velocities past 1,400-1,450 FPS offers no appreciable ballistic advantage. The physics of a sphere dictate that the harder you push it the greater the exponential increase of drag function that sphere encounters traveling through air. In tandem, the same is true for increasing the diameter and thus surface area of the sphere. That's why the old adage of big, slow pellets being ideal for geese will carry over from days gone by lead waterfowl loads to today's steel shot (or any other shot material). Since steel has such a low density at 7.86g/cc, shoving any size pellet past that "magic" 1,400 FPS range, +/- 50 FPS, does more harm than good; higher recoil, greater risk of pattern disruption, slower return to target for follow-up, more component in the shell (powder), and higher cost per shot for a ballistic advantage that is completely depleted in the first 25 yards. Even when shoved at 1,700 FPS the material just won't retain its energy and penetration down range. Further, if you are able to shove a steel payload past 1,900 FPS you will only see incremental gains in extending the increased energy potential.
The same can be said though for any material of higher density. You loose so much from throwing round balls faster that you really end up with what I SWAG as a 35/65 ratio on ballistic benefit to cost/detriment. I've shot some thumpers of lead loads using super hard and round plated shot with high antimony and typically the patterns have been atrocious to "meh", with no appreciable difference on game at normal and "extended" ranges. Federal used to put out a 12ga 2-3/4" 1,500 FPS 1-3/8oz load in this category that was impressive but not super useful, IMO. Fiocchi Golden Pheasant in a similar 1,485 FPS load can be considered much the same, although I have had much better luck getting it to pattern well out of new and old guns. The bottom line is though that the same pellets launched at 100-150 FPS less will have the same terminal ballistics past the 30-35 yard mark, and especially at 40+ yards.
It is a shame that physics has to come and ruin our party when it comes to these sorts of things as steel shot is very affordable when compared to the alternatives. Hell, if money and rarity wasn't a factor we would all be shooting a 19g/cc density super malleable shot that could be blended with tin and nickel plated to create the densest, most ballistically effective shot man kind has ever devised; GOLD.
Once you get to 9g/cc density though, the deficiencies (or should we say, limits?) of steel shot becomes even more apparent by penetration tests when the shot is all propelled at the most effective velocities for each shot material's density.
Now when it comes to something like a 3" 16ga?.... I can argue for and against that one. HAHA!
It would not bother me one bit to see modern shotshell technology and a 3" chamber applied. The 16, much like the 28, is such a wonderful cartridge as is. However, true fans of the 16 bore would most likely come to appreciate the efficiency of a sweet-16 magnum chambered shotgun capable of delivering the lower end of 12ga Magnum payloads. It might even potentially be the most efficient and effective bore ever if such a change was made. BUT, the recoil in a true 16ga framed shotgun would not be the most pleasant and that would be your brick obstacle to overcome.