Pellet velocity versus accuracy test: Part 9
by B.B. Pelletier
Joel’s winning photo is of his niece, Paysen. He was teaching her to shoot a Crosman 66 over Thanksgiving weekend.
Today, we’ll complete the testing of the four pellets at four different velocities in the Whiscombe rifle. The premise of this test has been to explore the effects of velocity on accuracy by shooting the same pellets in the same pellet rifle at four differing velocities. I will make today’s report and comment on how the test went, but this will not be the final installment of this test. There will be at least one more summary report that puts all the data into perspective. And if there are side issues to explore, maybe there will be more reports.
At this point, I think I know what I’m going to find when I look at all the data, but there have certainly been a few surprises in this test. And the surprises continue in today’s report. Let’s get right to it.
This time, the Beeman Devastators were averaging 772 f.p.s. Since this is a very lightweight lead pellet, at just 7.1 grains, I would have thought this velocity would be about as ideal as it gets. The pellets thought otherwise. Ten shots went into a 25-yard group that measured 1.073 inches between centers. You’ll have no problem counting all 10 shots, because none of them seemed to want to go to the same place.
However, I do want to draw your attention to the upper right portion of the group. There are 5 holes in a much smaller group measuring 0.399 inches. This is what the best 5 out of 10 shots looks like, and it’s a temptation to say that this is what the rifle/pellet can do. Think not? Well, in a national magazine, a popular gun writer who traditionally shows three-shot groups when talking about accuracy, recently published an article about .22 rimfires in which all the groups were 5 shots — very uncharacteristic for him. But when he reported the group sizes, he twice mentioned the size of 4 out of the 5 shots in those groups! In other words, he couldn’t resist the temptation to make the gun sound better than it really was — even when the evidence was right out in the open. That’s why I most often shoot 10-shot groups.
Beeman Devastators did not stay together this time. This group measures 1.073 inches between the two farthest centers. But look at the much smaller group of 5 in the right-hand corner. They’re both legitimate and a fraud at the same time. They were legitimately shot by the rifle in this test, yet they do not represent the true accuracy of the rifle at 25 yards at this velocity.
Crosman Premier lites
Next, I shot a group of Crosman Premier lites. They did just the opposite of the Devastators — grouping the best they did out of all four tests. The group measures 0.593 inches between centers. That says a lot for this pellet, but perhaps not everything. The velocity at which they traveled was an average of 732 f.p.s. Is it the velocity or something else that makes them so accurate? We shall just have to wait and see.
All shooting was done with care
Lest you think I relaxed at any time during this test, I assure you I did not. Each shot was fired with the same care as all the others. The bubble level was consulted each time just before the shot was taken. I now have the trigger breaking at less than 8 oz., so it’s perfection. I’ve even concentrated on my hold to make it as much the same from shot-to-shot as I possibly could.
Next up were the Beeman Kodiaks. These were the pellets that had proved to be the most accurate up to this point in the test. This time, however, they opened up to 0.864 inches between centers. You can see that 8 of the 10 shots are in a much tighter group, but let’s not go there yet. The group you see represents how well these pellets did at an average velocity of 658 f.p.s.
We have long since passed the point at which the 16.1-grain Eun Jin super-heavyweight pellets are accurate; but just as the United Nations continues to grant its chairmanship to members of the smallest third-world countries, so we continue to shoot this pellet with each test — pretending that is has some part to play. Last time, Eun Jins printed some two-plus inches below the aim point. This time, with the velocity averaging 501 f.p.s., they dropped 6-3/8 inches! They were so low that I had to reorient a target to see them print on the paper.
The group measured 1.724 inches between centers. That’s larger than last time.
Like I said in the beginning, I’ll look at today’s results right now, but there will be another report dedicated to the entire test. I want to know what you readers think about this, because a lot of what I do ultimately comes from you.
What I see in today’s results sort of implies that accuracy falls off at lower velocities. Now, I don’t happen to believe that’s the case; but except for the Premier lites, that’s exactly what happened today. That suggests that something else is causing the larger groups. Perhaps vibration? Maybe that needs to be explored.
Looking at the Beeman Kodiak group, and to a lesser extent the Premier lite group, it seems like pellet selection might improve these two groups significantly. I shot all the pellets exactly the way they came from the tin or box. No special sorting technique was used. Would accuracy have improved if I had weighed these pellets and examined them critically before shooting? That’s a question so intriguing that I’m almost compelled to test it next.
On the other hand, no weighing or sorting will improve the groups made by the Beeman Devastators or the Eun Jins that much. They’re just what they are, as the openness of their groups suggest.
If I didn’t have a lot of experience shooting pellets at lower velocities, I might be tempted to make up some sort of explanation as to why they did so poorly. But I’ve shot other slower air rifles that exhibited excellent groups at 25 yards, so it seems like it must be something else. That’s where the thought of vibration comes in. With the Whiscombe, I can alter the vibration nodes with the Harmonic Optizmized Tuning System (HOTS).
That makes me think of something else. You know how we always say that to find the best pellet for a given gun you have to try them all? Maybe what you’re doing is finding the pellet that responds best to the way the airgun vibrates!
You tell me what you think I should do next. I won’t promise to do it all, but I will read with great interest what you have to say.