Max. Shot Sizes & Non-Toxic Energy Equivalents
By John Dyer, Senior Wildlife Manager, Auckland/Waikato Fish & Game Council (and Shotgun Editor, NZ Guns & Hunting magazine). July 2011.
The Wildlife Regulations have long stipulated the maximum size of shot that hunters may use for taking gamebirds. It states:
"No person shall use in any shotgun used for the purpose of hunting or killing of game any cartridge containing any shot greater in size than size BB", (Section 18a Wildlife Regulations, 1955).
The purpose of this has been to prevent or at least minimize any injuries to adjacent hunters in maimais spaced 100 yards / 90 meters apart. That’s because the energy the shot retains is primarily a function of its size, weight and speed. Lead shot size BB is a nominal 0.180" in diameter and is made of lead with a mixture of alloys such as antimony which have a small but not insignificant effect on it’s nominal weight.
The arrival of non-toxic shot means that the long-accepted arbitrary distinction of the Wildlife Regulations, against shot larger in diameter than BB, is no longer sufficient. That’s because each non-toxic shot type has an entirely different specific gravity. Steel, (more properly called soft-iron shot), is much lighter than lead. Hevi-shot as the name suggests is heavier. Also, it is the case that, to overcome the poor efficiencies of non-toxic shot, the manufacturers have frequently resorted to driving shot at much higher velocities. Some non-toxic shot types respond to this better than others. So a simple rule that allows all existing and future non-toxic shot types to be no larger than "BB" in size, which was historically adequate when shot was invariably made of lead, is no longer adequate. Also, we need to be aware that manufacturers are experimenting with shotgun pellets much larger than was formerly commonly used when lead was king.
Already non-toxic shot larger than BB lead has been imported into New Zealand and this can be expected to continue. Particularly with larger waterfowl species, such as geese and swan, it is desirable that importers bring in non-toxic ammunition with such larger shot sizes because these kill more humanely especially in lighter-than-lead steel sizes. However we need to be aware that, if some of these larger sizes of shot imported contain more energy than lead BB, then the relative risk to adjacent hunters is also elevated. From the ballistic program "Ballistics for Windows" we know that an ordinary 12 gauge, 2,3/4" shell firing BB pellets at high-velocity can do serious damage to humans out to 57 meters and will still pierce skin at 240 meters. While this suggests that even lead BB may be too dangerous to use, in practice, this law has served us more than adequately for many decades. In fact, this regulation probably predates 1953 and can be traced to much earlier legislation in the 1920’s. But we now need to bring the 50-year-old Wildlife Regulations up to play by providing an equivalency for each new non-toxic shot type on the market.
To find these equivalents, I have used loads available in recent manufacturers catalogs, such as Remington and Federal Ammunition Companies. While the weight of the 2 charges, the velocities, shell length and other factors vary, do not be distracted by this as the physics of pellet size/weight x speed doesn’t change just because a shell is a ¼" longer or the gauge size is either larger or smaller. In many cases, exact comparisons between different non-toxic shot types is not yet possible because of the properties of the respective new products. Manufacturers simply haven’t learnt yet how to make some of the larger non-toxic pellet types, or for commercial reasons don’t bother. Consequently I’ve compared, using Ballistics For Windows, the nearest available equivalent to Lead BB for each non-toxic shot type. I’ve also included the next shot pellet size up, fired from the same cartridge, (i.e. at the same speed), to demonstrate why the pellet I’ve chosen is the cut-off point. I am not saying that any of these pellets are "safe" at 90 meters range. Rather, the degree of risk is equivalent to that we have lived with for the last 50, (or perhaps 85), years, apparently successfully as accidents are rare.
Incidentally, it is still the case in New Zealand, Australia, the UK and USA, that Imperial, (not metric), measurement units are used for shotgun ballistics and I make no apology for this. The expression BB shot is, in fact, an Imperial one, meaning 0.180" diameter. The shotmaking sieves that determine the ultimate shot sizes are designed to specifications laid down in the late 1890's and do not lend themselves to, nor warrant clumsy nominal metric designations being arbitrarily given to each size. Nor do any English language ballistic texts use such a metric system and rarely is shot sold in NZ marked in metric. However, all ranges and energies are shown in metric as the Wildlife Regulations now specify that maimais should be 90 meters apart, not 100 yards.
Also note that the figures used are nominal ones. Actual weights of pellets can vary somewhat between producers and even individual production runs. Another factor is the quantity and type of different hardening alloys used for the intended end-use, the grade of product, any surface plating used and the presence of shot-buffer or otherwise. However, the trend is clear enough regardless.
Firstly, let’s consider the standard which the Wildlife Regulations has imposed. We should be mindful that until the mid 1976 no 3" shell of any gauge was legal in NZ, so it is appropriate to use a 2,3/4" shell as our standard.
Lead BB shot (0.180"), standard velocity.
A 1, 1/4oz load of BB, buffered or unbuffered, fired from a 12 gauge, 2, ¾" shell @ 1200 ft/sec. full choke, at sea level, will carry it’s 63 BB pellets at an average of 157 m/sec. velocity at 90 meters and each pellet will retain 6.88 Joules of energy.
The above is a standard field load, which has for decades been widely used in New Zealand for gamebird hunting. Switching to a magnum shell increases the number of pellets in the payload, but since the velocity is the same, the individual pellet's energy remains the same. If anything, magnum shotgun shells are loaded to somewhat more conservative velocities to keep pressures down. Many hunters equate "magnum" with more energy and therefore more risk to themselves at a distance. However whether or not a shotgun shell is a magnum one is largely irrelevant to this discussion about individual pellet energy - it is magnum rifles whose bullets carry more energy than 3
standard calibers, and this is perhaps where some of the confusion comes from. However, within standard length shells, it is possible to produce relatively high-velocity loads....
Lead BB shot, high velocity.
A 1,1/4oz load of BB lead pellets, @ 1330 ft/sec. Pellets retain 166 m/sec. at 90 meters and so retain 7.68 joules of energy.
As these shells have long been in use in NZ, then for practical purposes the maximum energy threshold the Wildlife Regulations has implicitly set for the last 50 years has been approximately 7.7 Joules of energy at 90 meters.
Because steel shot is only about 5/8ths the weight of lead, it has a considerable energy handicap at longer range. However because it is harder than lead, it is possible to shoot it out of a shotgun at much higher velocity without damaging or destroying it in the process. The increased velocity helps it overcome some of it's significant weight handicaps. But at 90 meters, the lighter steel shot has more rapidly shed it's velocity. Steel BB pellets are but a shadow of the performance of lead shot:
Steel BB shot, highest current velocity.
A 1, 1/8oz load of 81 BB steel pellets, @ 1500 ft/sec. from a 3" 12 gauge. Pellets retain 131 m/sec of velocity at 90 meters and just 3.40 joules of energy.
To get back the energy of lead, users of steel need to use larger pellets. For instance, Remington’s fastest load of TT, (0.210"), steel pellets:
Steel TT shot, highest velocity.
A 1, 3/8oz load of 62 TT steel pellets, @ 1450 ft/sec. from a 3,1/2" 12 gauge. Pellets retain 148 m/sec at 90 meters and carry 6.89 joules of energy.
If we increase the pellet size to F, (0.220"), we pass the implied energy level that the Wildlife Regulations set. However, the pellet pattern is now so thin that, I note, Remington, for instance, does not include this loading in their catalog. So these calculations are largely hypothetical though TT shot has sometimes been available in NZ.
Steel F shot, highest velocity.
A load of 54 F steel pellets, @ 1450 ft/sec. from a 3, ½" 12 gauge. Pellets retain 154 m/sec at 90 meters and 8.54 joules of energy.
With bismuth shot, the pellet weight is much heavier than steel, and almost as heavy as lead - not quite as much once the necessary and unavoidable tin alloy is put in however, (tin overcomes some of the natural brittleness of bismuth). This means that it is necessary to step up to bismuth T to get to the Wildlife Regulation’s 7.7 Joules of energy limit. Whereas steel can be driven faster than lead, bismuth being relatively brittle cannot and, for instance, the Bismuth Cartridge Company of the US doesn’t load any of it’s BB pellets faster than 1280 ft/sec and the BBB and T shot loads I've shown are hypothetical as they are not yet commercially available. This is because each pellet has to be moulded 4
and this is proving technically difficult to do commercially. BB is the largest size currently loaded.
Bismuth BB shot, standard velocity.
A 1,3/8oz load of 80 BB bismuth/tin pellets, @ 1280 ft/sec. from a 2, ¾" 12 gauge. Pellets retain 146 m/sec at 90 meters and 5.17 Joules of energy.
Bismuth BBB shot, standard velocity.
A 1,3/8oz load of 68 BBB bismuth/tin pellets, @ 1280 ft/sec. from a 2,3/4" 12 gauge. Pellets retain 152 m/sec. at 90 meters and 6.61 Joules of energy.
Bismuth T shot, standard velocity.
A 1,3/8oz load of 58 T bismuth/tin pellets, @ 1280 ft/sec. from a 2.3/4" 12 gauge. Pellets retain 158 m/sec. at 90 meters and 8.30 Joules of energy.
Tungsten steel is a similar weight to lead. It seems that Tungsten-Steel BB is the largest pellet that can be accepted without exceeding the 7.7 Joules of energy Wildlife Regulation standard:
Tungsten-Steel BB shot, high velocity.
A 1,1/8oz load of 61 BB tungsten-steel pellets, @ 1400 ft/sec. from a 3" 12 gauge. Pellets retain 161 m/sec at 90 meters and 6.76 joules of energy.
Tungsten-Steel BBB shot, high velocity.
A 1,1/8oz load of 52 BBB tungsten-steel pellets, @1400 ft/sec. from a 3" 12 gauge. Pellets retain 168 m/sec at 90 meters and 8.60 Joules of energy.
Tungsten-Matrix is a different product to Tungsten-Steel. The fastest load made by manufacturers Kent Cartridge Company USA is 1400 ft/sec and shot size #1 (0.160"), is their largest diameter. So a BB shot size is hypothetical. However, once again, BB shot size is the cut off:
Tungsten Matrix BB shot, high velocity.
A 1,1/4oz load of 67 BB tungsten matrix pellets, @1400 ft/sec. from a 2,3/4" 12 gauge. Pellets retain 163 ft/sec at 90 meters and 6.94 Joules of energy.
Tungsten Matrix BBB shot, high velocity.
A 1,1/4oz load of 57 BBB tungsten matrix pellets, @ 1400 ft/sec. from a 2,3/4" 12 gauge. Pellets retain 169 ft/sec. at 90 meters and 8.82 Joules of energy.
is made by Federal Cartridge Company. It appears to be slightly different to Tungsten-Matrix made by Kent Cartridge Company. For instance, a 0.110", (2.8mm) #6 pellet of tungsten-polymer has an average weight of 2.8 grains per pellet and a count of 225 pellets per ounce. This compares with a 0.111:, (2.817mm) # 6 pellet of tungsten-matrix which averages 2.02 grains per pellet, with a count of 217 pellets per ounce. Since these are average counts and vary between different production runs, the 5
small margin of difference begins to blur. For all practical purposes, the 2 products could be treated the same.
Hevi-shot is manufactured by Environ-Metal Inc. The manufacturers have supplied a density of 12.0 grams per cubic centimeter in advertising and claim it compares to lead at 10.9 and steel at 7.8. Remington, who market Hevi-shot state that it is 10% heavier than lead and 54% heavier than steel shot. It is currently being sold in New Zealand. A conversion factor shows that 12.0 grams/c.c. is equivalent to 0.434 pounds cubic inch. The largest shot currently available from Remington appears to be #2, but here I use Ballistics For Windows to compare hypothetical B and BB sized Hevi-shot:
Hevi-shot B shot, high velocity.
A 1,1/2oz load of 83 B Hevi-shot pellets, @1400 ft/sec. from a 3, ½" 12 gauge. Pellets retain 172 ft/sec. at 90 meters and 7.53 Joules of energy.
Hevi-shot BB shot, high velocity.
A 1,1/2oz load of 70 BB Hevi-shot pellets, @1400 ft/sec. from a 3, ½" 12 gauge. Pellets retain 179 ft/sec. at 90 meters and 9.65 Joules of energy.
To maintain lead-BB energy equivalency at 90 meters, I have previously recommended the Wildlife Regulations should be amended to ensure non-toxic shot should not exceed the following sizes:
"No person shall use with any shotgun used for the purpose of hunting or killing of game any cartridge containing any shot greater in size than:
lead size BB, (0.180" – 4.6mm)
steel (soft-iron) size TT, (0.210" – 5.3mm)
bismuth size BBB, (0.190" – 4.8mm)
tungsten-steel size BB, (0.180" – 4.6mm)
tungsten-matrix size BB, (0.180" – 4.6mm)
Tungsten-polymer size BB, (0.180 – 4.6mm)
Hevi-shot size B, (0.170" – 4.3mm).
After some discussion, it was decided to use a more generalized equivalency rule, to cater for new types of shot coming onto the market. This puts the onus on the importer, (who of course will have access to the wholesaler and/or manufacturer for specifications), to ensure the new shot is as safe as the old Lead BB. The alternative would be to restrict the sale of every new non-toxic shot type until it had been listed in the regulations the following year. The regulations now read:
Shot Size. No person shall use, in any shotgun used for the purposes of hunting or killing game, any cartridge containing any shot size having a larger retained, per-pellet energy at 90 meters than lead BB". 6
Keep in mind that importers and retailers may stock larger sizes without breaking the law. Fish & Game have no authority to seize these products, (as some hunters have suggested we should), unless they are found in the field being directly used for gamebird hunting which is an offence. To avoid this situation occurring, we have contacted all our ammunition selling game-licence stockists to advise them of the situation Indeed, importers have also asked us for clarification and there is much good-will to comply.