Back on Track
Gary Wain is back on the perfect pellet trail, with a quartet comparison
Gary Wain returns to his obsession with pellets – the different shapes of .177s
With the wonderful distraction of the BSA factory visits behind me, it’s time to crack on with my quest to find the perfect pellet. Since the arrival of the R2a chronographs from Lloyd at Blackpool Air Rifles, I’ve examined the ballistic characteristics of pellets. Firstly, of identical design, but with one in .177 and one in .22, and then in the second test, I looked at .177 and .22 pellets of identical design, but weighing the same amount. The results of the latter of these two tests really baked my noggin and it wasn’t until I refreshed myself of the principles of ballistic co-efficient, and more particularly, coefficient of form and sectional density, that the results actually began to make sense.
This month, I intended to compare varying shapes of .22 with .177, but as the data set obtained from such work was potentially too large to digest – remember, I am a bear of very little brain – I decided instead that this month I would focus solely on the .177 pellet, and in particular take a look at four pellets of near identical weights, but very different head shapes.
SIMPLE AND COMPLEX
When we talk about ‘shape’, what we really need to be thinking about is ‘coefficient of form’, but personally, as much as I like to think I understand ballistics, the concept of coefficient of form is at the same time both the most simplistic, and the most complex part of the ballistic coefficient equation to understand. We can all, to some degree, take it for granted that we understand the concept that pointy things pass through the air easier than blunt-ended things, in the same way that we comprehend that spears pass through the air easier than lumps of four by two, but attempting to put a numerical value behind that is not a simple task.
What we have then, are four pellets from four different manufacturers, all in the .177 calibre. Don’t worry all you fans of .22, we shall be getting to you soon enough. Although all of these pellets weigh around the 8.6gr mark, they are each of varying head design. The reason I’ve selected these pellets is not that they were the best of the last round of ballistic testing – we’ll get to that later in the series – but because they all produced reasonably similar results in those previous tests. With the benefit of the pair of chronographs, my intention is to put
numerical substance atop the previously laid plaster foundations.
So, this month we’ll be looking at the following pellets. First up, we have the bench mark, bog standard, domed pellet, in the shape of the 8.4gr Air Arms Diabolo, and when I say ‘bog standard’, I am perhaps doing it something of a disservice. The reason for this less than flattering description is purely to identify it as the ‘vanilla’ pellet among all the other exotic flavours. OK, so maybe that’s also not a great analogy, but I think you get the idea.
The second pellet in the line-up is the Bisley Superfield. On the face of it, this 8.5gr pellet looks like a domed pellet, but peer a little closer and you’ll see that it has a small, ‘hollow pointesque’ indentation in the front of the dome, along with a pronounced lip as the dome tapers to the skirt. In previous testing, this pellet performed reasonably well, so we were keen to put some numbers into the frame.
Third on the list we have the H&N Hornet. These chaps have a rather large, and rather obvious brass point, darty bit protruding from the main lead body of the pellet. In previous testing, we saw that they tended to over-penetrate the ballistic material and leave a fairly inconsequential ballistic core. Would this round of testing confirm those findings? Or were we to find out something extra special about the Hornet? Last on the list we have the JSB Premium Exact. These wadcutter pellets weigh in at a rather ‘exact’ 8.26gr, and from previous testing were among those that gave the largest wound cavities.
ON WITH THE TESTING
With the oven on, and the meat thermometer firmly in place, I set about warming the terracotta wax to its optimal 20 degrees. Unfortunately, I’d run out of tin foil with which to line the tray, and from previous dealings with terracotta wax I knew it made an ungodly mess when warmed up. So, at this point, most chaps would be fretting about their good ladies asking about the disappearance of a certain oven tray. As it happens, I do all the cooking in this particular household, and so it was the work of moments to make said oven tray ‘disappear’, to the extent that it never even existed. Even so, if you’re intending to do your own ballistic testing, I can highly recommend lining the tray with foil.
As before, I made each of the wax samples
“with the shooting distance set in the region of 15m, I commenced firing”
a measured 40mm thick, to represent the width of our quarry, and equally importantly, so that they could stand up under their own weight. I then headed to the newly revised, and much more amenable ‘range’, and with the shooting distance set in the region of 15m, I commenced firing upon the terracotta wax with the four pellets.
The first pellet to be fired was the Air Arms Diabolo Field. At 8.4gr, this pellet is one of the most popular pellets on the market today, and not without good reason. It’s well made, consistently accurate and regarded as the go-to pellet by many knowledgeable shooters. On entry, this pellet had a velocity of 629fps, with an exit velocity of 389, giving it a loss of 240fps in velocity as it passed through the clay. Energy wise it went from 8.92 ft.lbs. to 2.81ft.lbs., recording a reduction of 6.11 ft.lbs. of energy lost.
The next pellet to be tested was the 8.5gr Bisley Superfield. Weighing just one tenth of a grain heavier than the AA Diabolo, this pellet should have given similar results, were it not for the small indentation in the nose of the pellet giving it something of a hollow point appearance. As it happens, the Bisley lost 327fps in velocity, and 6.23 ft.lbs. in energy, putting it slightly ahead of the Diabolo.
The third pellet to leave the barrel of my Daystate Pulsar was the H&N Hornet. As previously described, this 8.8gr brass-tipped pellet is the heaviest, and the pointiest in this round of testing. As pellets go, the Hornet looks the bee’s knees.
That said, the Hornet did punch its way through the ballistic clay with gay abandon, surrendering 275 fps of speed, but only 5.39 ft.lbs., of energy.
The final pellet in this month’s test group was the wadcutter JSB Premier Exact. This diminutive pellet, with its rather blunt and to the point aspect, surrendered a whopping 395 fps of speed, and a very impressive 6.32 ft.lbs. of energy, putting it at the top of the leader board for this round of testing.
So what are we to make of these results? Well, as the associated core samples tell us, the wadcutter comes out on top, with the Bisleys not far behind, a mere fraction ahead of the Diabolos and with the pointy Hornets bringing up the rear with a no less respectable set of results. What the numbers don’t reveal is that as well as showing the best set of data, the wadcutters left a truly devastating internal wound cavity in both this and previous experiments.
We don’t have data on how accurate these pellets are, and to what extent the values gathered with regards to ballistic capability alter, as the distance to target increases. If you’re sharper than the average tool in the box then you’ll already have worked out where we’re heading. If not, then tuck your hands in and hold on! I
AA Diabolo and Bisley Superfield, but which one’s which?
Which pellet had the energy to knock over the clay?
All about the same weight, but which will work best? The H&N left an impressive entry hole.
The figures obtained, back up the previous core sample results.
The guards for the R2a chronographs are certainly earning their keep.
The Pulsar and Viper Pro combination make the testing a piece of cake.
The JSBs are packed to protect their heads.
The pellet tray on the Pulsar earns its keep.