An-depth look at BioAmmo’s eco-friendly loads
weighs in on the latest 24g target loads from BioAmmo, in lead and steel shot options
Moves away from conventional plastics are clearly well under way and the speed of change visibly increasing in pace with ever more products made from, or wrapped in, some form of ‘eco-friendly’ biodegradable biopolymer. Cartridges have come in for close attention ever since the BBC programme Drowning in Plastic aired some years ago and now heightened with moves to phase out lead shot.
Suitable materials that resolve the many issues raised and provide commercially viable alternatives are not readily found or sourced. Like it or not, steel shot is the only cost-effective option for the majority of volume use and brings issues of its own. Being very hard, steel shot requires stronger wads, especially for larger shot sizes and heavier loads. Extra-thick HDPE (highdensity polyethylene) has been the proven solution until now. It remains to be seen if the newly developed biopolymers can fulfil the most arduous duties.
The Spanish BioAmmo company has shown great foresight and unwavering commitment to help shooters fight the evolving eco wars. Interestingly, this company makes its cartridge cases and wads from the biopolymers it has developed. These are used for its game and clay loads, in both lead and steel shot types. We received samples of each shot type for clays for review.
Clay Shooting magazine, now part of Sporting Gun, first reviewed clay target loads from BioAmmo in 2020. The company has spent many years researching, developing, patenting and manufacturing biopolymers made from vegetal sources. The result has enabled it to sell cartridges with ‘plastic’ wads and loaded in ‘plastic’ cases that contain, as printed on the cartons, 0% plastic.
BioAmmo cartridges
The latest BioAmmo cartridges are packaged in colourful cartons clearly portraying the ‘green’ nature of the products within. The lead shot cartons have a lichen-covered tree trunk image in the foreground with a forest floor background, and the steel shot carton depicts a verdant woodland overhead view that borders a bright blue coastline: very attractive, different and appropriate.
The 70mm-long parallel tube biopolymer cartridge cases have a lightly ribbed external surface. Their length allows for the greater volume the same weight of steel shot requires and also helps with reliable feeding and extraction in semi-automatic shotguns.
Lead shot cases are light green in colour, while the steel shot case tubes are light grey; there is, therefore, no chance of confusing, or accidentally mixing, the cartridge types.
Both have a 15mm-tall, brass-coated steel head and use primers from Spanish company Maxam; flash holes are covered with paper discs, which are coloured red for the steel shot loads and white for lead shot to denote primer type to match the propellants.
Propellant powders are also manufactured by Maxam. Precise compositions are not divulged, but they are from the Maxam CSB series of single-base powders, with greyishlight green disc-shaped powder grains. Both types burn very cleanly and are evidently high energy, producing impressive velocities with modest charge weights. Powder
charge weights averaged 23 grains in the lead shot load and 21 grains in the steel shot cartridges with Proof Laboratory test velocities results of 422m/sec and 420m/ sec respectively. Very quick, and in the case of the steel shot load, within 3m/sec of the maximum velocity permitted by CIP Rules for standard steel shot cartridges. (This velocity restriction is a major bone of contention and a topic we shall doubtless hear much more about in the future.)
Bio wads
Key to both the cartridges’ performance and future success are the ‘bio’ wads, which are manufactured from the new, brown-coloured biopolymer. This colour helps wads blend in with earth and leafy ground during the time it takes for them to decompose. Note that this biopolymer is ‘bio-compostable’ and not water soluble as some eco plastic wads are; it will not, therefore, dissolve in water.
A commonly asked question is “How long will it take for these wads and cases to decompose?” The answer is, it depends. Being compostable and biodegradable, the conditions for decomposition vary. Composting requires burying and confinement in soil and so on, and the bacteria, temperature and humidity will all affect this process. Left lying above ground will take a lot longer than in a composter. Cases and wads I left lying in my garden last year are still there. I suspect that in a very dry area, it will take a considerable time for them to fully decompose. The good thing is that they are 100% conventional plastic free, however long it takes.
Biopolymer wads weigh slightly more than typical HDPE wads: the lead shot 24g wad weighs 50 grains – five or so grains more than a typical plastic wad – and the steel shot 24g wad weighs 60 grains.
The wads for steel and lead shot are, of course, very different. Steel shot, being significantly less dense than lead, takes up about a third more volume for similar shot load. The lead shot wad cup is 16.5mm long compared with 25.5mm for the steel wad shot cup. As both wads are the same 45mm overall length, it means the steel wad’s collapsible centre section is 9.5mm shorter than the lead shot wad.
The shot cups being much longer in the steel shot wad means there is less space for a collapsible centre section to cushion the shot.
Being so much harder than lead, the steel shot will not be significantly damaged by the acceleration forces that wad centre sections are designed to minimise. However, a shorter cushioning centre section can also cut any slight reduction in felt recoil force benefits. This can make some steel shot loads feel more ‘punchy’ than a similar weight and velocity lead shot load.
Both types have the shot cup petals moulded during manufacture and not cut as steel shot wads often are.
Lead shot
The lead shot pellets are of high quality, as were those of the earlier 28g loads tested. The antimony content is high and is, in fact, printed on the cartons at 3.6% Sb. This is close to the typical figure used in high-grade competition cartridges. Crush test results of 26.5% confirm this. Hard shot, as proven in many tests, helps with good patterns.
Pellets are also well graded for size, with the bulk being within a tight 0.0025in tolerance; they are well polished with
graphite for a bright, smooth surface finish. Shot load weights averaged spot on 24g.
Steel shot
The steel shot also proved even in size, with almost all pellets measuring between 0.101in and 0.103in in diameter. This size consistency, combined with minimal deformation on firing, is helpful in retaining shorter shot strings for greater effectiveness at range.
The steel shot looks very different to the lead. It appears to have a passivated coating to prevent rusting in storage. This process, producing a light brown surface, not shiny as with the lead shot, could be mistaken for early oxidation but is not.
Shot loads also weighed out very consistently at 16 grains under 24g (370.4 grains). This amount totally fills the shot cup so I suspect this shot load is to ensure all steel pellets are contained within the shot cup. The slightly reduced weight still contained an average 23 more pellets than the lead load.
How they performed
The laboratory proof reports show excellent ballistic results. Both shot types are very fast indeed, with each recording virtually identical velocities exceeding 420m/sec; these speeds rank among the fastest of
clay target cartridges. I’m not a speed freak, but I know a great many shooters do take high velocity as a major plus point; you will find very few cartridges faster than these.
My caution with speed primarily concerns recoil; greater velocity means more recoil relative to shot load weight. These loads, both being 24g, counter the high recoil (momentum) levels with the lighter shot load, which was around 10Ns (Newton seconds) for both.
For comparison, a typical 28g clay load at the more usual ‘fast’ velocity of 400m/ sec gives around 11.2Ns momentum. The felt recoil of both 24g BioAmmo loads was correspondingly perfectly manageable.
Observations
Testing new cartridges, especially products with the latest bio credentials, is always interesting and challenging. Some observations were made during my tests, which were investigated. The first concerns the new wads and, more specifically, the material they are manufactured from. I noticed when collecting fired wads that some of the gas seals of the steel shot wad exhibited cracks.
My initial thoughts were that this would affect ballistics, with gas leakage resulting in a wider than usual velocity spread but 10-shot Proof Laboratory results showed this not to be so. The recorded SD figure of 5.8 is a typical good result for shotgun cartridges, which shows that, despite any cracking, the wads still sealed the gas very effectively even at these high velocities.
The recovered lead shot wads did not show this same tendency and SD was similar at 6.5. I raised this with the importer and BioAmmo replied. It acknowledged that cracking can occur and it is working with its biopolymer developer to see if a more flexible option can be found.
Very close inspection of recovered steel shot wads also revealed some tiny pin-prick holes in the shot cup petals. The lateral vector forces upon acceleration and travel had evidently resulted in the pellets pressing into the plastic sufficiently hard to produce this effect. Finding these prompted me to thoroughly clean the bores of the test guns and examine with a bore scope. No signs of any scoring or barrel contact from steel pellets were found.
Thinking this through, I suspect that the piercing occurs in the first inch or so of travel, maybe inside the case upon ignition (or at the forcing cone) after which velocity increases more slowly and pressures drop significantly. Outward vector pressures will reduce proportionately and so the steel shot appears not to touch the bore even though the wad could make you think this. I raised this point also and I must applaud BioAmmo on its speed of response and frankness. It has noticed this occurrence too and carried out tests. Though it doesn’t have an immediate answer, it was able to tell me that its testing revealed some other wads also produce such pin pricks without causing problems.
Producing a long-standing and highly developed, high-duty product such as a cartridge wad from completely new material is bound to raise some difficulties. BioAmmo recognises this and is working to further develop its product, which it is standing by.
BioAmmo cartridges are also being tested as part of a series of Sustainable Ammunition Days by BASC. I contacted the organisation to check and it appeared unaware of any issues to date from these days, where a great many shooters will have tried them.
A key factor in any shotgun ammunition is being capable of producing good patterns; an important part of the final acceptance of a quality custom-built gun was to demonstrate the gun’s ability to pattern well with a quality cartridge.
Good patterns
Rest assured that both the lead and steel shot cartridges produced good patterns. The lead shot cartridge did what highperformance, high-antimony lead shot cartridges often do: pattern more closely – recording more pellets in a 30in circle at 40 yards – than the nominal choke boring of the test barrel. The BioAmmo 24g lead shot load produced 72.6% patterns from the nominal Imp Mod barrel. That’s 2.6% above full-choke pattern density from a nominal 65% barrel and a sign of excellent ammunition.
Most of us will have read that steel shot patterns tighter than lead due to being
“The laboratory proof reports show excellent ballistic results”
harder. I haven’t yet done enough tests with steel shot to know for myself if that is usually the case. What I do know is that here, the steel shot BioAmmo load did not match the lead shot pattern density.
Pattern quality and regularity were fine, but actual density was lower. Even with 23 more pellets per load, the steel patterns had an average 11 pellets less in the 40-yard pattern from the same test barrel. A very interesting result. I shall be testing more steel shot loads in the future.
Testing on clay targets, the results were very good. The lead shot loads crunched edge on and quartering departing targets very convincingly: I had to remind myself these were 24g loads from the kills at extended range. I was surprised at the ultimate distance I managed to break clays with the steel shot loads too – over 40 yards. Not quite so convincingly – I walked back from a trap to see how kills were affected. Steel shot loses velocity/energy faster than lead, so that was expected. It was clear, though, that steel shot, even a 24g load, will break further than one might think likely.
BioAmmo cartridges are currently being offered at very competitive prices, around £220/1,000 for each type. That’s typical of current fibre wad load prices and so this is a great offer for clay shooters to try ‘bio’ without costing them the earth.