|20" Circle Impacts|
|30" Circle |
|77 (30" Circle)|
The Lyalvale 2″ cartridge is so far removed from what most people consider a “normal” cartridge that it is hard to know whether to judge its capabilities against all other cartridges, a set standard, the capabilities of a .410 cartridge or in its own terms. Ultimately all of those viewpoints probably have something to contribute to this analysis, but make for necessarily complex (and in some ways, contradictory) conclusions.
Clearly, a cartridge containing only 102 pellets on average cannot reasonably be expected to perform against a set standard of 120 pellets in the standard circle at a given distance. We could, of course, consider lowering that standard to 100 pellets, (or 80 pellets, or 60…) and trust that luck would see our quarry killed and not wounded, but there is a reason that our collective experience has settled on pattern densities of 120-140 pellets as the minimum requirement: all other factors provided for, they work.
Since the 120-140 pellet standard is used on this website (and almost everywhere else serious investigation into the performance of shotgun cartridges takes place) we cannot reasonably compare the Lyalvale cartridge against the broad range of commercially available cartridges. This, initially, leaves us two approaches: analysis of the cartridge in its own terms and via comparison with other .410 cartridges.
The former approach speaks for itself and is elucidated by the calculation of percentage pattern densities for the cartridge. The latter approach is perhaps justifiable since, in many cases, .410 cartridges can be marginal, even at normal shooting ranges and the Lyalvale cartridge can be treated simply as a particularly incapable example of that class.
In percentage (i.e. its own) terms, it is difficult to describe the performance of the 2″ cartridge as anything other than appalling. We have been used to seeing pattern percentages in the 90%-99% range for patterns shot at a distance of 20 yards. This has been the case essentially irrespective of loading and case length, though we admit that the smallest shot sizes (i.e. #9 and smaller) and anything fired through a nominal cylinder choke may not always meet this standard.
The Lyalvale cartridge, by contrast, fails to achieve even a 90% standard with a ¾ choke and drops below 60% density using the lightest (0.005″) choking in the test gun. This is equivalent to a 40 yard pattern density of less than 20% (nominal True Cylinder = 40%). The cartridge simply does not put enough of the original shot charge into the circle to justify a label of even “average” performance.
Undoubtedly there are reasons for such poor performance. It is a consistent feature of the testing done by the SmallBoreShotguns team that a rolled turnover and card – doubtless unavoidable in a case this small – leads to interference with the shot column as it reaches open air: some pellets are deflected away at angle so large that they do not even hit the (42″) pattern squares, let alone fall in the circle.
Furthermore, many of the pellets and both wads are likely damaged by the 1″ jump between end of cartridge case and chamber edge. If the wads expand to chamber diameter during this time, they will be sheared on the edge of the chamber as they enter the barrel, potentially damaging the wad and allowing combustion gas to pass by and interfere with the shot. If the wads do not expand to fill the chamber, combustion gas will pass through to the shot there instead.
The advantages to performance conferred by a larger shot size, #6, are not sufficient to outweigh these serious disadvantages. It would be informative to fire the cartridge in a 2″-chambered gun, to see if these effects are mitigates to any noticeable degree.
In comparison to the other .410 cartridges tested by the SmallBoreShotguns team to date, this loading gives the worst performance in both percentage and absolute terms. The latter should not be surprising given the cartridge is severely handicapped by its size; that the former is true may or may not be a product of the conditions under which it was tested.
An Alternative Analysis
In spite of the evidence available, the SBS team were not content to simply leave analysis of the 2″ cartridge without making our best efforts to a) compare the cartridge with others tested on as equal terms as we could contrive and b) find something positive to say about it – at the very least, because it’s cute.
One of the facets of pattern analysis which we don’t often employ directly on this website is that of effective pattern area. This is largely because, for the purposes of comparing different brands of ammunition, comparing absolute performance of many cartridges for a fixed pattern area is a more straightforward approach, and easier for our readers to follow (it is also fraught with confusion!). Stating that a cartridge places 150 pellets in the standard circle at 40 yards and that another places 120 in the circle under the same conditions makes for an obvious conclusion: the first cartridge performs better.
What this simplistic approach hides is the fact that shotgun patterns are not linear. That is to say, the pellets are not evenly distributed throughout the circle. Rather, they tend to be distributed about the point of aim, approximating the Normal distribution, showing the highest density of pellets close to the point of aim and progressively lower pellet density as one moves away from it. The 120-140 pellet approximations used above and elsewhere (e.g. the Eley Diary) take this effect into account.
Understanding this behavior allows us to make another kind of comparison between cartridges which is less straightforward, but which allows us to directly compare cartridges, including those like the Lyalvale 2″ cartridge which do not contain enough pellets to meet a specified minimum standard pattern density.
We will detail the steps required for calculating and comparing effective pattern areas in an upcoming article. The calculations are not straightforward and this is not the place to provide them in detail.
In short, however, because the pellets in a pattern are concentrated towards the center, a 20″ circle drawn around the point of aim should have a higher linear pattern density than a 30″ circle drawn about the same point. Because of this, we may find that even without the minimum number of pellets sufficient to provide any effective 30″ pattern, sufficient density may exist in a smaller area to make some part of the pattern effective. Using the ratio of the areas chosen, we can determine an equivalent 30″ circle pattern density from a larger or smaller area, giving us a direct comparison of cartridge effectiveness.
The trade-offs, of course, are that increasing or reducing the pattern area requires the shooter employing such a pattern to be proportionately less or more accurate in placing that pattern on the quarry and that the approach is mathematically questionable.
The data in the table above gives pellet counts for a 20″ circle and, linearly-extrapolated, the number of pellets which would fall in an equally densely-populated 30″ circle. We can see that in all of the 20-yard cases, the equivalent 30″ circle density exceeds the 120 pellet standard, meaning that game hit by the part of the pattern surrounded by the 20″ circle should be killed effectively. For 30-yard ranges, we see that one of the ¾-choke patterns essentially meets this standard, with the other falling just short. We caution again, however, that this mathematical analysis is of questionable basis and likely will not translate to equivalent performance in the field.
Other features of the data: The pellet count of 77 in a 30″ circle from appears to be an anomaly – we may have used a 20″ circle in this case also and failed to record that fact. Additionally, one should not read too much into the identical pellet counts for the 20-yard patterns using 0.005″ and 0.010″ chokes. We do not believe that this indicates outstanding cartridge consistency – indeed, most of the design factors work against this – but rather a stunning coincidence.
Allowing for better-than-double normal accuracy then, the Lyalvale cartridge could (just about) be used to 30 yards. In hands of an ordinary shooter however, it is probably quite useless unless one aims the shotgun like a rifle. Collectively, the SBS team rather like the 2″ cartridge in principle, but one would have to be trying deliberately to damage one’s chances given the number of 2½” / 3″ chambered guns available compared to those of 2″.