Posts Tagged ‘Beeman Kodiak pellets’
by Tom Gaylord, a.k.a. B.B. Pelletier
Today, blog reader Paul Hudson shares his Theoben Crusader rifle with us. The Crusader is not as well-known in the U.S. as some other Theoben models, so this will be an interesting report.
If you’d like to write a guest post for this blog, please email us.
With its walnut stock, the Theoben Crusader is a large, handsome airgun.
The Theoben Crusader is a high-power breakbarrel airgun, identical in size and performance to the Beeman R1. Its stablemate, the Theoben Eliminator, seems to get far more press since it’s one of the most powerful breakbarrel airguns available. That power comes with a high price — a cocking effort of 50+ lbs. — that most shooters are not willing to endure for very long. The Crusader, on the other hand, is far easier to cock and is a more practical airgun. Based on the used guns I’ve seen for sale, either the Crusader sales are much lower or people tend to keep them. Few are seen on the usual airgun sales sites or at airgun shows.
The Crusader is a high-quality spring-piston rifle.
Measuring a full four feet in length and weighing 8 lbs., 3 oz. unscoped, the Crusader is a large airgun. Mine is .177 caliber; but .20, .22, and .25 calibers are also available. The Lothar Walther barrel is 16 inches long, and a muzzlebrake is standard equipment (.22-caliber Crusaders have an Anschütz barrel). There are no baffles in the muzzlebrake. No open sights are supplied by the factory, making an optical sight a necessity. My rifle has a right-hand walnut stock, but an ambidextrous stock can be had from the factory as a no-cost option. The pressed checkering does give enough grip to be functional. A very good non-slip recoil pad keeps the rifle in place. No plastic parts are used on the rifle.
The metal work on the Crusader is first-rate, with a high polish that’s typical of many British airguns, and the wood-to-metal fit is excellent. Allen-head screws are used throughout the gun except for one screw that secures the triggerguard.
Behind that screw, a Schrader valve allows the owner to change the air pressure in the gas spring. Note the thumb rest in the stock.
A gas spring
Like all Theoben springers, the Crusader uses a gas spring, not a metal spring. Cocking is butter-smooth and requires 38 lbs. of effort. The piston includes a sliding weight that reduces piston bounce and felt recoil. A Schrader valve at the rear of the receiver allows the pressure in the gas spring assembly to be adjusted to vary the power of the gun. Upon firing there’s no spring twang or vibration, just a quick snap. The sound level is moderate. And, due to the size of the gun and careful tuning, the felt recoil is mild for the power level.
The lower bolt is pinched between the breech block and the locking wedge to prevent vertical barrel movement. Note the taper at the rear of the barrel to make pellets easier to seat.
The barrel pivot setup on the Crusader is a little unusual. Most breakbarrels use a breechblock that’s close to the width of the forks of the receiver. Wide, thin shims may also be present between the breechblock and the receiver forks. The pivot bolt is then tensioned to the point that the lateral barrel movement is constrained. The breechblock on the Crusader has much more side clearance. Belleville washers are used to control the lateral movement. Belleville washers are cone-shaped from the side and are actually considered to be springs. A second bolt behind the pivot bolt mates with a hook on the back of the breechblock. The locking wedge pulls the breechblock tightly against this bolt to control the vertical movement of the barrel. Like many classic Webley rifles, the Crusader takes a bit of a slap to open the barrel for cocking.
The unusually wide breechblock/fork clearance is visible from below the action. (The photo is overexposed, leading to the yellow stock color. This was necessary to bring out the detail within the cocking slot.)
The Evolution trigger of the Crusader and other models has been criticized by some; and given the price of the gun, that may be justified. No creep is felt in the first stage, but the second stage is not as crisp as a Rekord trigger. As the gun came from the factory, the second stage breaks cleanly at 1 lb., 13 oz. The safety blade resides in front of the trigger and automatically sets when the gun is cocked. It can also be manually reset. Overall, I would rate the Crusader trigger as very good, just not quite as good as a Rekord or TX200 unit but not a reason to avoid the gun.
The trigger blade is almost straight; the automatic safety resides in the front of the triggerguard and is pressed forward to fire.
Velocities with the Crusader are similar to what’s found in a Beeman R1, and some lighter pellets in a .177-caliber rifle will go supersonic and ruin the accuracy. I tried a couple H&N Field Target Trophy Green pellets, but they traveled almost 1200 feet per second and missed the bullet trap at 25 yards. Extreme spreads with most pellets were under 20 feet per second, and a few varied by less than 10…very good for a springer.
These are the velocities the Crusader can deliver with the selected pellets.
Many pellets gave 5-shot groups around an inch in size at 25 yards. Several gave very good accuracy, including a few that surprised me. To get the best accuracy shooting from the bench, I had to hold the airgun loosely with my right hand and keep my left hand open. If I let my fingers touch the forearm, I had to make sure I didn’t squeeze the gun at all or the groups would open up. In other words, use the classic artillery hold. You cannot grip this airgun tightly and get good accuracy; it’ll take practice and proper technique to get the best results.
All groups were 5 shots at 25 yards, and the sights were not adjusted for the different pellets. It was interesting to see the difference in the points of impact. Predator Polymags and 8.4-grain JSB Exacts shot especially high in relation to the other pellets. Unfortunately, neither 7.9-grain Crosman Premier lites nor 10.5-grain Premiers heavies did much better than one-inch groups at 25 yards. While that’s not too bad, a number of pellets did far better.
Five H&N Baracuda Hunters made this 0.50-inch group.
Five Predator Polymag pellets made this 0.40-inch group. Good enough for hunting.
Gamo TS-10 surprised me with a 0.45-inch group; but their size seemed a bit inconsistent, and there were some flyers with this pellet.
Skenco Big Boys gave this nice 0.43-inch group. The group is almost twice as wide as tall.
The 13.4-grain JSB Monster also produced a 0.43-inch group.
The Crusader really liked the 8.4-grain JSB Exacts, as this round 0.24-inch group shows.
Best accuracy came from the Beeman Kodiak pellet. This group above is just 0.23 inches.
Adding it all up
Why buy a Crusader? After all, it costs just over $1000, and that price will keep many away. Compared to a Beeman R1, the size and power are identical. The R1 has a better trigger, but the Crusader has a better firing behavior due to the gas spring. The Crusader also has a far nicer stock, better metal finish and includes a factory muzzlebrake. Between my Crusader and my R1, the Crusader shoots more pellets accurately and will shoot slightly smaller groups, probably due to the fine Lothar Walther barrel. Unfortunately, the Crusader is more hold sensitive than my R1.
Both rifles should last a lifetime with proper care. It’s possible to upgrade an R1 with a new stock, a gas spring, muzzlebrake, etc., but you’ll end up spending more than the cost of the Crusader and still do not have the nice metal work. If you can afford it, the Crusader offers very good accuracy in a nicely finished package.
Theoben Production ceases
In October, 2012, Theoben Ltd. in England announced that they were entering liquidation (bankruptcy). It remains to be seen whether another company will take over production rights for Theoben springers.
by B.B. Pelletier
I’ve covered this material before, but it was long ago, and we’ve grown in readership lately. New shooters read about group sizes and assume there’s an accurate and foolproof way of measuring them. That’s simply not the case. The great barrel maker Harry Pope once spent half an hour with a magnifying glass and a caliper to measure the size of a group; and in the end, he revised its published size by about 1/64 of an inch! So, if a world-class marksman (he held several world records) and barrel maker has trouble doing it, what hope is there for the rest of us? I’ll address that question at the end of this report.
I’m not going to delve into the history of measuring groups, because there’s too much material to cover in less than a book chapter of perhaps 5,000 words. And most of you would either be asleep or reading another website if I got down to the minute details involved in the dozens of different ways it has been done over the ages. So, today I’ll plunge right into the subject with the belief that we all measure our groups the same way and don’t care how it was done 100 years ago.
It’s customary to measure shot groups from the two centers of the bullets that are farthest apart. But the new shooter wants to know how to find the center of a hole reliably. The answer is simple — don’t look for the center, find the edge. If you measure from the extreme edges of the two bullet (or pellet) holes farthest apart and subtract one bullet diameter from the answer, you have just subtracted the radius from each of the bullet holes. The radius is the distance from the center of a hole to its edge — so in fact you have just “found” the two centers of the holes in question.
But where’s the edge?
To do it this way, you need to find the edge of each hole, and that’s where it gets hard. If you’re shooting wadcutter pellets, the holes will be sharp, round and easy to measure; but if you’re shooting domed or pointed pellets, the holes will be much more vague. This is where those who shoot centerfire rifles have it easy compared to airgunners. Because their bullets go so fast, they leave sharp, round holes in the target regardless of the shape of the bullet.
It’s pretty obvious why wadcutters are the darlings of the paper target crowd!
Even pointed bullets tear clean holes when they rip through targets at close to 3,000 f.p.s., like the 87-grain spitzers from this .250/3000 Savage.
Where the edge of the hole really is…is always a guess. Always! But with careful work, you can get the error range down to just a few tens of thousandths of an inch.
I use dial calipers for measuring group sizes. I don’t own a digital caliper, so I’m relying on a caliper that has a mechanical dial calibrated in thousandths of an inch. Actually, the dial is just part of the measurement. For the gross measurement, you have to read the scale on the staff of the caliper, as well. The dial just gives you the final thousandths of an inch.
A dial caliper is an easy way to measure groups, but a ruler will do if that’s all you have.
When I measure groups, I do not look at the dial. I adjust the jaws until they just touch the edges of the two holes I’m measuring. This usually takes several attempts; and the stronger the light, the easier it is to be precise. The target paper must be flat to do this right, so the best way is to lay the target on a well-lit table and then place the dial caliper over the group and work the caliper jaws down until they touch just the edges of the holes. If there isn’t enough light on the target, I’ll use a powerful flashlight — a tactical flashlight — to illuminate the target.
Can groups be measured without a caliper?
Yes, they can. In that case, you need the most accurate ruler you can get your hands on. A steel machinist’s rule is the best tool to use. But lacking that, you can measure groups with an ordinary school-grade ruler. However, once you’ve taken the measurement, it’s best to convert to decimal fractions that run out to thousandths of an inch — because nobody will be impressed with a group that measures 3/8 inch, but everyone will admire a group that’s 0.375 inches! I’m joking, of course, but not as much as you would like me to be.
Finding the edge
Have you noticed that my groups often end up in the white target paper instead of in the black bullseye? My brother-in-law thinks that means the guns I shoot are inaccurate because they don’t hit the black bull — but I do it so I can find the edge of the pellet holes easier.
When you look for the edges of the holes, there are clues. Sometimes the pellets will leave a round lead ring where they tear through the paper. You can see this on the white target paper but not on the black. Other times there will be rips that extend radially away from the edge of the hole. These rips are part of the diameter of the pellet or bullet, as I will now show you.
See how the bullet hole in the white stands out but in the black is obscure? Much easier to measure this .45/70 hole when it’s in the white. Notice, also, that the radial rips are part of the bullet’s diameter.
One way to get the best results is to push a pellet into one of the holes (try not to use either of the two measuring holes for this) and see how the skirt of the pellet passes through the hole. That will give you a good sense of where to put your caliper jaws in relation to the rips or the lead ring.
I’ve said this before, but it bears repeating: any group measured to the thousandth of an inch is off by up to twenty-five thousandth of an inch. I may have even said a larger error number than that.
Why are people so “inaccurate”? Well, do you know what twenty-five thousandths of an inch looks like? For your entertainment I will now illustrate how large that is.
Twenty-five thousandths of an inch sounds big, but when you see it illustrated here as the space between the caliper jaws, it really isn’t. If you can measure a group this close to actual size you’re doing very good! The silver dime is on sabbatical, so this one is a stand-in.
When doctors disagree…
…who shall decide? If you could only attend one regional target match and watch competing coaches argue with the officials over measurements of a few thousandths of an inch, you would soon understand that measuring targets is an imperfect science. Always has been and probably always will be. At the Olympic and World Cup levels, the error has been reduced to less than a thousandth of an inch with sound transducers and triangulation…but it still isn’t exact.
What hope do we have?
If this all sounds like magic or hokum, consider this — the more often you do this the more uniform your measurements will become. You may never get the measurement exactly right, and there’s virtually NO way to prove that you did or didn’t, but you will tend to err in the same way time after time. In time, your measurements take on a standard error that’s based on YOU. You become the standard!
by B.B. Pelletier
This report is another response to a viewer of our Airgun Academy videos. In episode 22, we say the following at 3 minutes, 20 seconds into the video, “When using real hunting pellets, you have to realize that the velocity and, therefore, the power is going to be significantly less [than the light pellets the rifle is advertised to shoot fastest].” A viewer took issue with that statement, so today I’d like to explore how airguns handle pellets of different weights.
There are three different types of airgun powerplants: pneumatics that store air under pressure and release it with the shot. This compressed air pushes the pellet and gives it it’s power. The pneumatic powerplant pushes the greatest volume of compressed air behind the pellet and, depending on design considerations, is potentially the most powerful type of airgun powerplant.
Spring-piston airguns store no air. They have a spring-powered piston that releases with the shot and moves forward to compress a very small amount of air that gets behind the pellet to push it. The pressure of this compressed air is very high, but the volume is very small; once the pellet starts down the barrel, the air pressure behind it drops off fast. By the time the pellet leaves the barrel, there’s very little pressure in the air behind it — especially compared to a pneumatic airgun.
Guns that use carbon dioxide act more like pneumatic guns, except that carbon dioxide is under less pressure than compressed air; plus, it expands slower because its molecule is larger than the atoms contained in compressed air. CO2 guns act like pneumatics to a point, and then they’re limited by their use of the larger CO2 molecule, where compressed-air guns, which are pneumatics, have much higher limits.
How it works
How does this affect the performance of an airgun? Most commonly, when the pellet weight increases. The power of a spring-piston gun decreases, and, of course, the reverse is also true. It’s not an absolute physical law, but only a general relationship. There are some design considerations such as the contact surface of the pellet with the bore and the lubricity of the lead alloy that can change this relationship slightly. However, the relationship still stands.
British airgun magazines have been talking about this since the 1980s. It’s very important to them because of their legal 12 foot-pound power limit. If a new pellet can come on the market and increase the performance of certain airguns that are currently legal so they exceed the legal limit of 12 foot-pounds, then the entire airgun community needs to be aware of it! Once it becomes known that a certain pellet can do that, the authorities will be using that pellet to test all airguns. Let’s put this relationship to the test today and see if it holds any water.
Using a .22-caliber Diana 27 spring rifle, I’ll shoot three different weights of pellets. If the relationship holds true, the lightest-weight pellet should produce the greatest power, the medium-weight pellet should produce the second-greatest power and the heaviest-pellet should produce the lowest power.
The .22-caliber RWS Hobby pellet weighs 11.9 grains and averages 490 f.p.s. in the Diana 27. That means it produces an average 6.35 foot-pounds of muzzle energy.
The .22-caliber Crosman Premier pellet weighs 14.3-grains and averages 459 f.p.s. in the Diana 27. It produces an average 6.69 foot-pounds of energy at the muzzle.
The .22-caliber Beeman Kodiak pellet weighs 21 grains and averages 352 f.p.s. from the Diana 27. It produces an average 5.78 foot-pounds of energy at the muzzle. I am aware that the Pyramyd Air website says the Kodiak weighs 21.14 grains; but the Kodiaks I’m using are several years old, and I’ve weighed them on an electronic scale at exactly 21 grains.
So, we already have an exception to the general rule, with the Premiers producing greater muzzle energy than the lighter Hobbys, where the relationship predicted the opposite. But the general trend does remain in force, as the much heavier Beeman Kodiaks produce significantly less muzzle energy than the lighter pellets.
Now let’s try these same three pellets in a tuned Beeman R1 and see what happens. If the relationship holds, we should see the lightest pellet making the greatest energy and the heaviest pellet the least, in a linear relationship.
The .22-caliber RWS Hobby pellet averages 817 f.p.s. in the R1. That means it produces an average 17.64 foot-pounds of muzzle energy.
The .22-caliber Crosman Premier pellet averages 750 f.p.s. in the R1. It produces an average 17.87 foot-pounds of energy at the muzzle.
The .22-caliber Beeman Kodiak pellet averages 575 f.p.s. from the R1. It produces an average 15.42 foot-pounds of energy at the muzzle.
Again, the Premier pellet stepped out of line by producing the greatest energy. But the Kodiak maintained the relationship.
What does this prove?
It doesn’t prove anything. It demonstrates a general relationship between pellet weight and power in a spring-piston airgun. You could test 10 more guns and get several more anomalies, including a gun that actually shot the heaviest pellet with the greatest power. In fact, I’ll tell you how to do that in a moment.
But if you tested 10 different spring-piston air rifles, you would probably still see the general relationship holding most of the time. I’ve been doing this for many years, and I’ve seen it happen too many times to doubt that the relationship does work as described.
How to beat the relationship
I learned, when testing several exotic tunes while writing the Beeman R1 book, that a heavy piston always favors the heavier pellet. So, simply adding sufficient weight to a piston will change everything. But it will also give you more piston bounce and poor performance with a broader range of middleweight and lightweight pellets — which is why the pistons of spring guns weigh what they do. They’re made to give the broadest possible range of performance within the expected power band of the rifle they were made for.
When I wrote the script for episode 22, I was thinking of spring-piston airguns when I wrote the line that the viewer took exception to. That’s because the huge preponderance of airgun hunters today use spring-piston rifles.
Before you jump down my throat for saying that, I do realize that there are thousands of hunters using PCPs; and in some warm spots, there are even hunters with CO2 guns. But that doesn’t change the fact that most airgun hunters in the U.S. still use spring-piston rifles today. I shouldn’t have made a broad statement like that in the video without qualifying it, and the viewer was right to voice his concern. We’ve added corrective text to the video at that point.
But this report isn’t really about that video. It’s about learning how pellet weight performs in an airgun. According to this logic, precharged guns develop more energy with heavier pellets and less with lighter pellets. So, let’s switch over to a precharged pneumatic rifle and run the same three pellets, to see what happens. If the relationship holds as it’s stated, the heaviest pellet should be the most powerful and the lightest the least powerful.
The .22-caliber RWS Hobby pellet averages 1035 f.p.s. in the SS. That means it produces an average 28.31 foot-pounds of muzzle energy.
The .22-caliber Crosman Premier pellet averages 982 f.p.s. in the SS. It produces an average 30.63 foot-pounds of energy at the muzzle.
The .22-caliber Beeman Kodiak pellet averages 882 f.p.s. from the SS. It produces an average 36.28 foot-pounds of energy at the muzzle.
So, this time, the relationship held exactly as predicted. You can expect the same relationship to play out in every pneumatic, regardless of the power level at which it performs.
Okay, I’ve explained an old relationship between pellet weight and performance. What about it?
A couple of things, actually. First, with the modern uber-magnum spring rifles, you can expect to see a lot of reversals in the relationship. That’s because they have heavier powerplants that are designed for heavier pellets. So, things may not be as cut-and-dried as you see here.
Second, I want those of you with chronographs to do your own tests and report the findings. That way, we’ll see if the relationship still holds over a much wider sample of airguns and pellets than what I’ve shown. Just choose pellets with weights that are separated by a good margin, so each one stands apart from the others.
And, finally, this is a lesson you need to internalize, because it’s fundamental — or at least I hope that all of us can prove that it still is. In the same way that a longer barrel increases the velocity and power in a pneumatic, this relationship will help you as you move forward in your airgun journeys.
by B.B. Pelletier
Dammion Howard (left) shows off some new airguns he found under the tree this year!
Happy New Year from Tom & Edith!
One nice thing about watching a TV program is that it only takes an hour or less to view. You have no sense of the man-weeks of work that go into a short production on screen. Sometimes, the same thing happens in the world of airgun blogs.
I won’t say I’ve been dreading today’s report; but from past experience adjusting the HOTS on the Whiscombe rifle, I knew it might take longer than anyone could imagine to get a good result. It’s easy to say, “Adjust the HOTS for optimum performance with a certain pellet.” Actually doing it is where you discover if it’ll be easy or hard. The report I have for you today was very hard.
I allotted several hours to the actual testing and adjusting that would have to be done. And with my past experience with the Whiscombe, I knew shortcuts the average shooter wouldn’t think of. Let me lay the groundwork so you understand what’s happening in this process
The Whiscombe harmonic optimized tuning system (HOTS) consists of a weight that can be adjusted in or out along the axis of the bore. A jacket around the barrel is threaded to receive this weight. The threads on the weight are very fine, and one turn of the weight moves it a millimeter in either direction. One complete turn of the weight constitutes 1mm movement of the weight.
Besides the weight, there are two other metal parts. One is a short collar that locks the weight in position after it’s been adjusted, and the other is a much longer cover that encloses the entire HOTS from sight. This longer cap doesn’t need to be removed from the weight to make adjustments, just provide access room for the special wrench that moves the weight.
Here you see the HOTS mechanism. The threaded weight is turned in or out of the barrel jacket by the wrench. Once the weight is where you want it, lock it down with the knurled collar on the barrel jacket. Then, install the long cap, and the job is done.
Where to start?
The problem is always the same: Where do you start adjusting the weight? The simplest way is to start right where you are — with the HOTS in the last position it was set. Shoot a group at that setting and go from there. I had that data, of course, from the earlier part of this test, so that’s where I began. Because the last transfer port is still installed in the rifle, the Beeman Devastator pellet still develops about 772 f.p.s.
When I shot a group at this velocity in the earlier test, 10 shots went into a group measuring 1.073 inches between centers. I was looking for a group somewhere near that size this time, too. It might be a little smaller or larger; but if it was a quarter-inch group, there was a problem with the results of the last test. The same care was taken with each shot; to do any less would have skewed the results or made them unreliable at the very least.
The first group shot in this test, shot with the same HOTS setting, measured 0.953 inches between centers. That’s 0.12 inches smaller than the group from the last test. I would call that in the same ballpark and therefore a confirmation that the last test was sound.
Adjusting the HOTS
Whiscombe says that there will be several sweet spots throughout a one-inch movement of the weight, which is approximately 25 full turns. He also says that one spot will be better than the others, and that’s the one to look for. He just doesn’t tell you how to find it, other than by adjusting the weight one turn at a time. But my experience told me that the sweet spot was probably not where the weight was at this time, so I turned it in (toward the receiver of the gun) four full turns and shot a second group. This is where my experience with the Whiscombe was supposed to pay off.
I wasn’t going to waste my time shooting 10 shots if the first 5 were spread out. Why bother? I wanted a tight group, and if inside 3-4 shots — or even 2, on one occasion — there was already a large separation, it was no use going further. I turned the weight in 4 full turns and shot another group. This group teased me with the first 5 shots in less than a quarter-inch, but the final 5 expanded that to 0.977 inches. Can’t be certain because of measurement errors, but no improvement at all.
Next, I tried the weight 5 turns in from the start point. The group was worse. I backed out to 3 turns in and got about the same size group as with 4 turns in.
At this point, I experimented with some subtle adjustments on a half and then a quarter turn. At 3.5 turns in, I got a group that was slightly smaller than the one at 4 turns, but it had one called flyer. I tried another quarter turn in and got 4 shots in a group measuring 0.998 inches between centers. Obviously, I wasn’t going the right way.
Okay, this wasn’t working. I adjusted the weight out in the other direction 9 full turns past the initial setting and shot another group of 10. This time there was some success, as the group measured 0.794 inches between centers. I wanted to call that the end of the test; but looking at the group, I knew it wasn’t enough of a difference to impress anyone. Even though it does show improvement over the baseline group, I would like to show a larger change since one of the Devastator groups in the earlier tests measured 0.616 inches. This group was too much larger than that. The gun should be able to do better if harmonics and not velocity was the main driving force behind accuracy.
By this time, I’d fired 49 shots in about 90 minutes. The test work had lasted much longer than expected, and I had to quit for the day.
A happy accident
The next morning, I was back at the bench and trying to complete the work. I figured I would adjust the weight out from the initial setting by a certain amount but as I tried to do that a happy accident happened. The front cover got stuck together with the weight; and by the time I noticed it, I’d already adjusted it 15-20 turns. Except, I had no way of knowing how many turns it was. I had to start all over, and this time from a random place that bore no known relation to the initial start point. Not that it mattered, except I didn’t want to waste all of the work from the day before.
I adjusted the weight at a point that looked to be well away from the initial setting. Then, I shot a group as a baseline. Or I should say I began to shoot a group. After 3 shots, I had a spread of 1.153 inches between centers — the largest spread of the entire test to this point. No sense finishing that one!
Past experience has shown that the sweet spots are often a couple turns in either direction. I guessed and turned the weight back in three turns from the starting point. And that was when it happened. The clouds rolled back, the angles sang and the rifle grouped like I knew it could. Ten shots went into 0.523 inches. That’s not only the best group of this little experiment with the HOTS, it also beats every group fired with the rifle during the main test conducted earlier.
With this kind of data in hand, I can say with some confidence that harmonics and not velocity is the main driver in how accurate a spring gun can be. I say this because the worst group shot during the velocity test was adjusted harmonically into the best group of the test with this pellet. There’s no chance in this group — it’s clearly much better than it was in the beginning.
Could the rifle shoot this pellet even better? Maybe. But it isn’t necessary to prove the point we were trying to prove.
Next, I want to adjust the rifle for Beeman Kodiaks at a higher velocity and test pellets straight from the tin against pellets that are sorted by weight. Today’s report should give everyone the confidence that, if a difference in accuracy is noted, it will be because of the pellets and not the gun.
by B.B. Pelletier
Kevin Currie is shown shooting a tuned .177 Gamo CFX with his son and dog. He says his CFX is scary accurate!
For those who celebrate Christmas, Merry Christmas from Edith and me! This is our last opportunity to wish you a Merry Christmas before Sunday, but I would like to hear on Monday from anyone who received an airgun, airgun-related gift or a firearm for Christmas. I’ll tell you what I got, too.
Today, we’ll look at the results of this test to see if there’s a direct inverse relationship between pellet velocity and accuracy. I’ll start with the results by pellet and see where that goes.
A word about the shooting technique
The first accuracy test I did was in Part 2 of this report. I found fault with that test, though, because of how I was shooting. I wasn’t using the scope level on the gun all the time, and I also wasn’t “seasoning” the bore by shooting several shots before starting a group. Some pellets seemed to need the seasoning, while with others it didn’t seem to matter as much. I reshot the entire first accuracy test and seasoned the bore for every pellet, plus I paid attention to the scope level.
The need for seasoning seemed to go away as testing progressed, but the scope level was always consulted for every shot. I know that the level improved the performance of every pellet that was shot. The jury is still out on the seasoning issue.
All the accuracy results seen here are not from the first time I shot the rifle, but the second. All were shot at the velocities indicated. Just the shooting techniques were adjusted as indicated.
In this test, the 7.1-grain Beeman Devastator was the “little pellet that could.” From the start, when it was averaging 1,216 f.p.s., this lightweight hunting pellet produced 10-shot groups under three-quarters of an inch at 25 yards. That went against the popular belief that supersonic velocities are harmful to accuracy.
The Devastator turned in the following performance at 25 yards.
Velocity (f.p.s.)….Group size
Okay, you don’t need a graph to see a problem here! This pellet is obviously way more accurate at 1,123 f.p.s. than it is at 772 f.p.s. Theory says that shouldn’t be because the first velocity is breaking the sound barrier, which is where all the accuracy gremlins are supposed to live.
Looking at the group size in relation to the velocity, it appears that 1,123 f.p.s. is the most accurate velocity for this pellet in this gun. That would entirely negate the theory that velocity destroys accuracy. So, if there is such a relationship, it must be subordinate to and less influential than some other influence. I think that other influence might be vibration, but that’s just a guess.
Crosman Premier lites
The 7.9-grain Crosman Premier lite was the next pellet I tested. Here are the results of all four tests at 25 yards.
Velocity (f.p.s.)…Group size
The Premiers did give a linear relationship between velocity and group size, though the two groups from the middle two velocities are so close in size that they could be the same. Measuring error is greater than the difference between these two groups.
The group at the lowest velocity is obviously the best of the four and by a wide margin. The data from this pellet isn’t clear as to what is causing the accuracy improvement. It could be either velocity or vibration. However, at 915 f.p.s., the pellet is going slow enough to be out of the transonic region, while at 1,057 f.p.s. it isn’t. I would have expected to see an accuracy gain at that lower velocity that’s greater than what we see here if the real problem is just velocity.
Next, I shot the heavyweight Beeman Kodiak pellet. It proved to be the most accurate pellet of this test and the only one that turned in a group smaller than a half inch. Please bear in mind that these are all 10-shot groups and are about 60 percent larger than they would be if they were only five shots. I didn’t shoot 10 shots for that reason — but because, in doing so, I reduced the probability error significantly. In short, I can trust that the group sizes shown are closer to reality that if I had shot two 5-shot groups and averaged them.
Kodiaks shot tight right from the start, even though the first group of pellets was actually close to or just within the transonic range. Since I didn’t keep atmospheric data for each day I shot, I can’t say where the sound barrier was exactly; and the transonic region, which is 0.8 mach to 1.5 mach, is calculated based on that. In practical terms, I know that 992 f.p.s. is pretty darn close to transonic, because the sound barrier can be anywhere from 1,050 f.p.s. to 1,125 f.p.s. depending on the temperature and humidity where I shoot.
Velocity (f.p.s.)…Group size
However, the groups don’t seem to support the velocity/accuracy relationship very well. It’s true that the first and second groups are too close to really say which is larger than the other, but the velocities at which they were shot are very important. One borders on the transonic, while the other is probably slower than transonic.
But look at that third group! When the velocity averages 819 f.p.s., the Kodiak loves this rifle! Is that a velocity thing or is that influenced by the harmonics of the rifle at that power level? I’m inclined to think that it’s the latter, though we do not have enough data to prove it.
The last group is the worst, though the velocity is getting pretty low for a pellet this long and heavy. We don’t know much from these results, either. But if it does turn out to be harmonics over velocity, then this pellet is probably the best one for the rifle, and the Harmonic Optimized Tuning System (HOTS) needs to be adjusted for it at around 900 f.p.s.
The 16.1-grain Eun Jin pellet is too heavy for the power potential of this air rifle. Although the Whiscombe JW 75 is a 30 foot-pound air rifle — that’s only in .25 caliber — when the heaviest pellets are used. In .177, it’s much closer to 20 foot-pounds and is, therefore, too weak to drive the 16.1-grain .177 Eun Jin fast enough for accuracy.
Velocity (f.p.s.)…Group size
Starting with the second group, I could tell that the Eun Jins weren’t going to do well. Like the Kodiaks, they’re also too long and heavy to make any conclusions regarding velocity versus harmonics. They just don’t give enough speed in this rifle to properly examine the velocity question.
A different look at the data
The “sweet spot” was different for every pellet. Each pellet had one velocity at which it grouped the best; disregarding the actual velocity, it went like this:
Fastest was best—>Eun Jin
Second fastest was best—>Devastator
Third fastest was best—>Kodiak
Slowest was best—>Premier lite
That, by itself, is a pretty good indicator that supersonic speed isn’t a problem, since the Devastator was supersonic when it produced its best group. One thing you cannot do is compare the group sizes…one to another…between the pellets. Let each pellet stand alone because there are far too many variables to make a cross comparison like that.
Was the Whiscombe a valid testbed?
Some thought the Whiscombe was the wrong gun to use because it’s so inherently accurate. I disagree. I think its accuracy makes the results all the more valid. Besides, controlling many of the magnum breakbarrel springers is too difficult and gets in the way of testing. They require perfect hold technique for every shot. The Whiscombe is much easier to control, which takes that variable out of the equation.
Some felt that only a pneumatic should be used since harmonics seemed to be causing accuracy errors. Well…that was the point of testing! Now we know a little more about how the pellets respond to supersonic speed, and it seems to me that it doesn’t matter as much as many, including me, have believed. People don’t just shoot PCPs. I do plan on testing this same sort of thing with a PCP whose velocity I can control over a wide range, and those results will also be interesting — but they don’t negate the value of testing a springer.
I used the Whiscombe for this test because, even when I altered the velocity, the harmonics of the gun remained the same. The powerplant always ran at full power, regardless of how fast it shot. And the barrel was always the same, too. The only thing that changed was the velocity.
What comes next?
I’m sure some of you will have additional interpretations to make about this test, and now is the time to make them known. My next step is to use the rifle as it is currently set up and adjust the HOTS to see what I can do to the size of the Beeman Devastator group. I’m thinking the HOTS can be adjusted to shrink it significantly. I have a procedure in mind to cut the time it takes to adjust the rifle because this can take hours if you aren’t careful! I’ll share that procedure with you in that report.
If I’m right about being able to tune the HOTS to get a small group at the average of 772 f.p.s., then the next thing I’ll do is shoot another group with the bubble level taped to hide the bubble. I won’t intentionally try to enlarge the group, but I just won’t be able to consult the bubble for every shot. That will result in another group that can be compared with the best group I’m able to shoot when the HOTS is tuned, because it will still be tuned for that group.
Finally, perhaps one additional test is needed. I’ll set the rifle to shoot Kodiaks in the high 800 f.p.s. range and adjust the HOTS for the best accuracy. When I get the best group, I’ll shoot one group of weight-sorted pellets against another group of pellets selected straight from the tin.
When all of this is completed, I should be able to state what I think are the most important components of accuracy. You’ll be able to see how much difference these things really have on group size. Most of you can’t adjust the harmonics of your spring guns, so you need to find the one pellet that shoots the best. Perhaps it’s time someone made a generic harmonic tuner for springers, again.
Mathias Moe Varga submitted the above photo of Miles Alexander Varga, who got in some shootin’ with his Crosman XT air rifle.
Today is Friday, and I’ve already written a couple reports this week that belong on a Friday blog, but a question came in from a shooter who will probably never read this report — yet, it was so intriguing that I wanted to answer it for you today.
This shooter owns a vintage Sheridan multi-pump pneumatic, and he’s been perplexed for years because .20-caliber Crosman premier pellets are not carried in stores. He remembers the old cylindrical pellets that used to come in the red and white tins and later in the yellow plastic boxes, but he doesn’t know if any .20-caliber pellets are still being made today.
Of course, they’re being made and in greater diversity than ever before. But you don’t typically find .20-caliber pellets at a sporting goods store, and they’re never found at a discount store. The best selection will be found on the internet.
His question made me think of this: Are today’s pellets better or worse than those of long ago? What I thought I would do today is find out which is better — the old pellets or the new.
I have been telling people for years that the .20-caliber Crosman Premier pellets in the cardboard box are noticeably better than the older cylindrical Sheridan pellets, but are they really? The only way to find out is to shoot some and see what happens.
I bought my Sheridan Blue Streak in late 1977, though I have also owned a vintage Silver Steak that was made between 1950 and about 1960. I no longer have that vintage gun, but the ’77 Blue Streak is still here, so that will be the test bed.
I used to buy Sheridan pellets in yellow plastic boxes of 500. They were the only .20-caliber pellets on the market when I bought them, but Dr. Beeman changed that in the 1980s when he began bringing in European spring guns in .20 caliber. Twenty caliber still occupies third place out of the four smallbore airgun calibers (.177, .20, .22 and .25) in terms of popularity, and its position is currently being threatened by a resurgence of interest in .25 caliber. Both .177 and .22 calibers are so far ahead of these other two calibers that there’s really no comparison when it comes to sales and usage.
Beeman’s pitch was that the .20 caliber was a great compromise between .177 and .22, but that pitch never quite caught on. Many shooters felt the truth was just the opposite — that .20 was both more expensive than the .177 and not as effective on game as the .22. You can argue this all day long and never change anyone’s opinion, but the truth is that there just aren’t as many great pellets in .20 caliber as there are in .177 and .22.
However, if there’s even just one good pellet, maybe that’s all we need. And the Crosman Premier pellet may just be the one.
I thought I’d test-fire several groups with my Blue Streak at 25 yards. Because it’s a multi-pump that takes some time for each shot, I’m going to shoot only 5-shot groups, but I’ll shoot several with each pellet. I’ll pump the rifle 6 strokes per shot because I’m shooting at 25 yards. That should give me decent accuracy, though I’m only using the open sights that came on the gun.
As I write this, I’ve not yet fired the rifle, so I have no data to consider. I do think the Crosman Premier will shoot more accurately than the old cylindrical pellet, but we’ll have to test it to see.
It’s been about two years since I shot the Blue Streak, so I oiled the pump head with Crosman Pellgunoil before starting. Then, I fired a single shot at the bull 25 yards away. It hit within about one-quarter inch of the aim point, so I finished that group and changed targets for the next.
The first three groups are all Crosman Premiers. I think the groups speak for themselves.
These three groups of Crosman Premiers were easy to put side-by-side because they’re so small. They were shot in order from left to right. The groups measure from left to right — 0.749 inches, 0.911 inches and 1.088 inches between centers.
Next, I tried the vintage Sheridan cylindrical pellet. Once more, I verified that the first shot was close to the aim point, then no more checking.
The first group of Sheridan pellets looks like I wasn’t trying, but I assure you I was. I really gave each shot everything I had.
Group two was better but not really good. I was relieved to discover that the reason was the pellet and not me. However, it gave me an idea. After group three with the vintage pellets, I would shoot a fourth group of Premiers, just to see if I could still shoot. I thought I might be getting tired at this point.
The third and final group of vintage Sheridan pellets confirmed that they’re not that accurate. It was in between the first and second group, even though I was doing my best to aim precisely.
Was I tiring out? I had to know, so I shot a fourth group of Crosman Premiers that had established themselves as accurate pellets.
This final group of Crosman Premiers shows that I was still shooting about the same as at the start of the test. It measures 1.106 inches between centers, which fits in with the first three Premier groups.
As long as I was shooting the rifle, perhaps I should shoot a group with one other pellet that’s given good results in the past. The .20-caliber Beeman Kodiak is actually a medium-weight pellet — at just 13.27 grains. I shot only one group, but it seems to confirm that this pellet is in the same class as the Premier for accuracy.
An interesting pattern
When I took the last target down from the pellet trap, the pattern in the fresh cardboard that backed all targets was quite interesting. Though I made no attempt to mount each of the eight targets in the exact same place, the cardboard tells the whole story about where all the pellets went.
Final thought for the day
This was written and tested on a Thursday — yesterday to everyone who is reading it on the day it is first published. I had been planning on going to the range to shoot some firearms yesterday, but the weather wasn’t cooperating, so I shot at home, instead. I’d planned to shoot my .32 cap-and-ball rifle, and shooting the Sheridan was very similar. You have to take time before each shot to get the gun ready so you’re extra careful to make every shot count. Also, going at this pace calms you and soothes you. I felt wonderful after this shooting session. Contrast that to shooting some uber-magnum springer that cocks like the bow of Hercules! Give me the slow lane every time.
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.