Shotgun Lethality Tables: Comment, Discussion, and Criticism
For
numerous reasons, shotshell lethality and effectiveness have been largely
ignored over the last 15 years. In an article entitled “Bismuth,
The Ballistic Potential” in the American Rifleman, Ed
Lowry discussed what was learned from the two extensive mortality studies
at Patuxent and Nilo Farms: “Both programs
also disclosed that if two pellets deposited the same amount of lethal
energy, the smaller one's energy is more lethally effective.”
Lowry continues, explaining that “the much
touted theory of No. 2s “compensating” for steel's low density,
and thereby matching lead No. 4s, is rudely rejected by an elementary
law of ballistic behavior.” Lowry also mentioned, “Steel's
density cannot be increased, its pellets cannot be made rounder, and its
scouring hardness cannot be made much softer. This tells us that steel
shot is now as good as it will ever be. Thus, the doctrine that steel
is ballistically equivalent to lead is emphatically contradicted by the
laws of physics and the measurements at Nilo.”
However, Ed Lowry was not totally dismissive of steel, either. Ed wrote, “Our shotshell program confirmed the enormous importance of pellet shape on ballistic performance. Thus what we really learned from Patuxent was not how well steel pellets do, but, instead, how badly lead pellets perform when they are unprotected from the crushing forces of setback.” Hunters aren't particularly interested in the facts about wounding ballistics. It is far easier to ignore boorish technical details, instead just humoring ourselves by thinking that if we somehow managed to kill some birds, then we can just forget about scientific knowledge and amuse ourselves with our own anecdotal version of non-knowledge.
For those interested in more factual data about wounding ballistics, that information is readily available. One of the very best and most comprehensive reference works to appear in many years is Firearms, The Law, and Forensic Ballistics, 2nd. Ed., by Tom Warlow (2005). Mr. Warlow's book is a must read for anyone with a sincere interest in firearm wounding ballistics and it is an excellent general reference work as well.
One of the most often quoted and misquoted tables is the Tom Roster Lethality Table.
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There is much to appreciate about Tom Roster's table, and much to lament about as well. While 12 gram/cc Hevi-Shot and Hevi-Shot alone is included (not generally available as loaded waterfowl ammo), other no-tox shot types are completely absent such as Kent Tungsten-Matrix, Bismuth, and Nice Shot. Nor is there any comparison to lead, as you might hope for in the case of pheasant and turkey. The only pheasant study of any consequence was by Tom Roster, only 1 oz. loads, and 3 lb. pen-raised released birds. In that study, #2 steel was found to be the most effective for pheasant at all ranges.
The Hevi-Shot data is no longer particularly helpful or relevant, as only 12 grams/cc density Hevi-Shot pellets are listed. High-antimony lead shot is in the area of 11.1 grams/cc density. Current Hevi-Shot branded product isn't as dense, most of its loaded product is less dense than lead and far less dense than listed on the Roster Table. Representative densities are Bismuth: 9.6 g/cc, Hevi-Shot Classic Doubles: 9.7 g/cc, Hevi-Steel: 9.4 g/cc, Hevi-Shot Duck: 9.8 g/cc, Nice Shot: 10.2 - 10.3 g/cc, and Kent TM: 10.8 g/cc. It has varied widely, with the rise in cost of Tungsten there is pressure to water down the density, so it pays to read the fine print, if indeed the density can be found at all. What Hevi-Shot did was misleading, after building a reputation with 12g/cc material, they passed off the less sense effective stuff while trying to keep it a secret: http://randywakeman.com/Hevi_shot_Fires_Back.htm . It is this type of frenetic, shameless marketing bluster that is of no help to the thoughtful wingshooter.
The data above is a bit of a nasty mess when "lead shot choke designations" are used. What a choke tube might be marked has little to do with what it does. Sometimes, astonishingly little so a listing of what might be marked on a choke tube is meaningless. The only rational way to compare choke performance is pattern percentage in a 30 inch circle at 40 yards. That is what performance really is, a choke marking yields no pattern percentage and is unhelpful as a result.
If we ignore the Hevi-Shot references, only meaningful with 12g/cc density shot, and further ignore the lead choke tube marking nonsense, then there is a good starting point. That is the minimum pellet count needed for the theoretical "clean kill." The biggest area of disagreement would be the notion that 210-230 pellets in a 30 inch circle is in anyway optimum for turkey. 100+ pellets in a 10 inch circle is considered minimum and most turkey hunters want far more density than that, myself included.
Yes, I'm being picky, but one area of confusion in the Roster table is "Large Ducks over Decoys" from 20-45 yards where, according to the chart, steel #2, 3, 4, 5, and #6 are all suitable. That's not much recommendation at all, and is violently inconsistent with prior studies that show #4 lead shot is more lethal than #6 lead at most all ranges. It gets even worse. For large, medium, and small ducks, #6 steel is recommended, but so is #6 12 gram/cc Tungsten (old Hevi-Shot).
This is a glaring oversight, as the data above clearly reveals. No. 6 steel has been redundantly well-shown to not nearly be the equal of #6 lead, much less a denser no tox. If you didn't know better, low-density #6 steel and high-density 12 g/cc tungsten alloy of the same diameter could be used interchangeably. I just have to just hope it is a tragic typo, for nothing smaller than #3 steel for mallards makes ballistic sense, with #2 having the clear advantage assuming satisfactory pellet count. Small wonder people are confused. The "Rule of Two" has been parroted for years and it works both ways. If you believe that #6 steel is somehow suitable for large ducks, then #8 lead would have been wonderful back in the day. It wasn't, of course, most people know better than that, the #6 steel references in the chart make no sense whatsoever, but they are there regardless.
On the basis of penetration, the effective range of pellets varies widely. For example, if you wanted 1.5 inches of penetration a 1330 fps lead load has that capability to 67.8 yards. A faster, 1500 fps steel load three sizes larger (#2) gets to only 55.3 yards with the same penetration potential. The "Rule of Two" limits you to 46 yards with 1500 fps #3 steel if you want the 1.5 inch penetration ability.
If you subscribe to the "Rule of Two," wanting performance approaching #5 lead than no steel shot smaller than #3 would be considered. If you are more inclined to go with the "Rule of Three," as I am, then #2 steel would be the far more reasonably based choice in an up to 45 yard large duck pellet.
We can simplify all this. For the hunter that patterns his shotgun, there are only two basic considerations. Firstly, we need pellets of sufficient penetration and resultant tissue disruption to actually be lethal at the ranges we use them at. Secondly, we need sufficient pattern density to ensure hits to vitally critical, quickly lethal areas of what we hunt, at the ranges we hunt at. That's the short version.
Copyright 2012 by Randy Wakeman. All Rights Reserved.
