Back on Track

Gary Wain is back on the per­fect pel­let trail, with a quar­tet com­par­i­son

Airgun World - - Contents -

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.

PEL­LET VA­RI­ETIES

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.

RE­SULTS

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.

CON­CLU­SIONS

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.

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