Posts Tagged ‘JSB Diabolo Exact Jumbo pellets’
by Tom Gaylord, a.k.a. B.B. Pelletier
Today is the start of accuracy testing for the Octane combo air rifle, and I’m going to make some changes. For starters, I’m going to give you the summary now. The Octane is a smooth-shooting, accurate air rifle. It’s everything the manufacturer wants it to be, and a couple of things they probably didn’t think about, on top of that. The rest of this report will justify and explain my summary.
Another thing, the Octane is different from any gas spring I’ve ever tested. Gas springs always fire fast, as in instantaneously. When the sear releases, the shot is over, and you usually know it from the sharp crack of sound and the painful slap to your cheek. The Octane fires slowly in comparison. There’s a lot of forward recoil and almost no vibration, and the discharge is very quiet, as I noted in part 2. I attribute this behavior to the Reaxis gas-spring design that’s reversed from the norm, and to the SilencAir silencer on the muzzle. Both apparently work as advertised.
I decided to just shoot 5 shots per pellet today, and to shoot the rifle with open sights at 10 meters. I wanted to get a good sense of how accurate it is before putting the walls of my house at risk. And what I discovered was that this rifle is fun to shoot! I normally don’t have much fun shooting a 20 foot-pound spring rifle, but the Octane is so civilized that it gave me a lot of confidence. By the time I’d fired the first 2 shots at the target, putting them into the same hole, by the way, I knew this day was going to be fun.
I held the rifle with an artillery hold, but the thumbhole stock makes you grip the gun harder than you normally might. So, I would have to call it a modified artillery hold. But the rifle cooperated, and there was noting to worry about. The muzzle heaviness holds the front sight steady on target once you’re dialed in.
The sights are fiberoptic, which destroy all attempts at precision, but by lighting the target brightly and sitting in a darker room to shoot, I could defeat the fiberoptic tubes and get a very sharp sight picture. When they don’t glow, the Octane’s sights offer a nearly ideal sight picture, and that was what made me decide to not mount the scope, yet. I wanted to have the fun of shooting with open sights since the rifle was cooperating.
The trigger is still quite heavy and very creepy, so I envy those who own their rifles and can modify them. If I could drop the release weight to under 4 lbs. and if there was a way to eliminate all the second-stage creep, this trigger would help accuracy greatly.
The first target was shot with 5 Beeman Kodiak pellets. This was when I first noticed how slow the Octane’s gas piston is. It feels like an airgun equivalent of a 45-70 single-shot. You feel the recoil and the rifle bounces around, but you know the pellet got out of the muzzle before all that started and that accuracy wasn’t affected in the slightest.
As I said, the first 2 pellets cut the same hole, though each made a distinctive mark. Then I stopped watching through the spotting scope and just shot the next 3 pellets. In the end, the group is larger than I would have liked for 10 meters, at 0.581 inches, but this is with open sights. Still, it is just 5 shots instead of 10.
Next, I tried the RWS Hobby pellet. It felt good while loading because it fit the breech tight but not overly so. And, though the point of impact shifted up a bit, the Hobby was quite accurate — putting 5 pellets into 0.368 inches! I thought that was remarkable. I couldn’t wait to test some more pellets!
Next, I tried the RWS Superdome. Here’s where you’re going to see something significant. RWS makes both Hobbys and Superdomes in Germany, and presumably they use the same lead alloy for both. And domed pellets are generally regarded to be the most accurate. Yet look at how the Superdomes did! They grouped horizontally, to exactly 1 inch, while the Hobbys stayed together.
You might try to blame me for getting tired at this point in the test, but there’s group coming that will show that I was still shooting my best. That’s one benefit of these 5 shot groups. They don’t tire me as quickly.
Now, for those of you who think I might have slipped up on the last group, I shot 5 Predator Polymag pellets next. They’re a recognized premium pellet, just like the Superdomes, and I’ve shown some great groups using them in recent tests. But not this time. Instead of the group stringing sideways, the Predator group were stringing vertically. Five went into 0.982 inches, so we won’t be seeing them in any future tests of the Octane.
If you have now decided that I’ve gotten tired and ho-hum, what’s so special about the Octane if this is the best that it can do — hold on! I saved the best for last. Actually, the Octane saved the best for last because the next group is the last one I shot on this day.
The 14.3-grain Crosman Premier pellet is sometimes the best pellet you can use in an airgun. And it is in the Octane test! Five Premiers went into a group measuring 0.245 inches between centers. It looks like only 3 pellets have passed through, but I did shoot all 5. This is very clearly and hands-down the most accurate pellet I tested in the Octane.
I already gave you the summary in the beginning of this report. Now you see the substantiation of what was said.
Several readers reported higher velocities than I got in the last test, and I was asked to change the breech seal. Well, I might do that, but frankly the rifle is shooting so nice right now that I don’t feel any urgency.
The Octane is unlike any gas-spring breakbarrel rifle I’ve ever tested. I wish the trigger was better, but it’s hard to argue with the accuracy or with the rifle’s firing behavior.
I will skip testing the rifle at 10 meters with the scope that comes in the package and go straight to 25 yards next time.
by Tom Gaylord, a.k.a. B.B. Pelletier
Just a word
Befoere I get started with today’s report, I want to say something about what happened this weekend. Friday’s airsoft report got a lot of comments. Among them are several questions about the technology of the guns. And some admissions that people didn’t think much of airsoft before they tried it, then they found their opinions changed drastically. That also happened to me, so I can relate to it.
But all you who don’t care for the subject don’t need to worry. This isn’t going to become an airsoft blog. I will continue to report on it at a low level, but I know this is an airgun blog, and that’s not going to change. I want to assure the readers for whom the subject of airsoft is not welcome that we are still going to talk about pellet guns and BBs guns for the most part. I will write a few reports on airsoft now and then, and I trust they won’t upset you too much.
Okay, that’s done. On to the topic of the day!
Today is our second look at the .22-caliber Octane combo from Umarex, and it’s velocity day. Before I get to that, there are a couple adjustments I wanted to make to the rifle. Let’s look at those now.
The first adjustment is the trigger. In the first report, I said the trigger is crisp but heavy. The adjustment screw adjusts only the length of the first-stage pull; so I adjusted it to be longer, and stage 2 decreased. Don’t go too far or the rifle will not cock at all because this adjustment does affect the area of sear contact.
I did go too far and had to call Umarex USA, where I learned that the Octane is supposed to come with a warning tag telling you not to turn in the adjustment screw more than one full turn. I went way past that, so all I had to do was turn the screw back out until the head stood even with the trigger blade — and the trigger was back to working again. For even greater contact, turn the screw so it stands proud of the trigger blade.
The second thing I wanted to adjust is the tension on the action forks because the barrel pivot was too loose. To do that, I normally take the barreled action out of the stock. But with this rifle, you need to be aware that the pins in the trigger are not held in and will fall out of the trigger if the action is tipped sideways. I didn’t know this, of course; and when the first pin fell out, it set me up for 45 minutes of work to get the trigger back together again. It seems that the trigger pins are held in place by the stock. Other airguns I’ve worked on have the same arrangement, and one solution is to put tape on one side of the trigger to hold the pins in place…and keep the trigger oriented straight up and down.
Each of the 6 free (not held by circlips or springs) trigger pins seen here is very loose in its hole and will fall out of the trigger if the gun is jostled or tipped to the side. They’re held in place by the stock. What appears to be a pin at the far right is actually a rivet.
Better still — what you can do (VERY CAREFULLY!) is remove both forearm screws and just LOOSEN the rear screw behind the triggerguard. Then the front of the action can be tipped up clear of the stock far enough to tighten the barrel pivot bolt and nut. I would advise against taking the action completely out of the stock. If you do, know how loose the trigger pins are and treat the rifle accordingly. When the pins fall out, the internal trigger parts start moving around. They’re fairly easy to align with their pin holes, except for the safety that takes a little fiddling since it’s a 2-piece assembly with an internal pivot. My advice is to leave the gun in the stock.
One final tip. When you tighten the stock screws, don’t tighten the rear stock screw (the one behind the triggerguard) too much or the trigger won’t function. It was not tight when I first took the action out of the stock; and I found that if I tightened it too much, the trigger would not work. Umarex told me the screw shouldn’t affect the trigger at all, but I’m just reporting on the behavior of my test rifle.
Now, let’s look at the velocity of the Octane. I’ve selected 3 popular lead pellets and one lead-free pellet.
JSB Exact Jumbo
The first pellet I tested was the 15.9-grain JSB Exact Jumbo. This is a popular and very accurate pellet in many airguns, and I think it may be accurate in the Octane. This pellet averaged 762 f.p.s. in the Octane. The low was 748 f.p.s., and the high was 787 f.p.s.; so the spread was 39 f.p.s. At the average velocity, this pellet produced 20.51 foot-pounds of muzzle energy.
This pellet loaded easily, perhaps too easily. I think it might be a little undersized for the Octane’s breech. That could affect the accuracy. We’ll see.
The RWS Hobby pellet weighs 11.9 grains in .22 caliber and is very tight in the Octane’s breech. It averaged 889 f.p.s. in the rifle with a low of 867 and a high of 902 f.p.s. So the spread was 35 f.p.s. At the average velocity, this pellet produces 20.89 foot-pounds of energy at the muzzle.
I don’t know how Hobbys will do in the Octane, but I suspect they’ll do well because of the tight fit in the bore. Of course, the Hobby is a wadcutter, so accuracy will fall off after about 25 yards.
The .22-caliber Beeman Kodiak dome weighs 21.14 grains, which makes it a very heavy pellet. In the Octane, Kodiaks averaged 682 f.p.s. with a range from 665 to 691 f.p.s. That’s a total spread of 26 f.p.s. At the maximum velocity, the Kodiak produces 21.84 foot-pounds at the muzzle.
My guess is that the Kodiak pellet might also be a good one for the Octane. If so, that’s great because it also produces the most energy of all the lead pellets tested.
Okay, the name of the game with pellet rifles these days is speed, and the RWS HyperMAX lead-free pellet at 9.9 grains is the way to get it. In the Octane, they averaged 1029 f.p.s. with a spread from 1022 to 1075 f.p.s. That’s a spread of 53 f.p.s., so the rifle is probably still burning a lot of fuel. At the average velocity, the HyperMAX pellet produced 23.28 foot-pounds of energy at the muzzle.
The HyperMAX pellet fit the breech very loosely. That’s probably where the extra velocity spread came from, as more dieseling was generated by less pellet resistance. I doubt this pellet will do very well in the Octane because of the loose fit.
The rifle recoils noticeably in both directions, but there’s no vibration, whatsoever. Nearly all rifles with gas springs have a sharp buzz that hits you in the cheek, but the Octane doesn’t. In fact, aside from the recoil, it’s a very smooth-shooting spring rifle.
Remember that I had to adjust the trigger for a very definite stage-2 let-off. That affected the trigger-pull a lot. I was able to adjust it back to a release of 7 lbs., 14 oz. with very little creep. It’s heavy, as I noted before, but I think it’s crisp enough to do good work. We shall soon see!
The Octane IS NOT LOUD!
When I first tested the rifle it was very loud. And the sound persisted for longer than I felt the dieseling of a new airgun would last. But during this test the rifle suddenly became MUCH quieter. Obviously, it had been dieseling and I didn’t know it.
I originally told Edith it was a 3.7 on the sound scale when I tested it, and she adjusted the loudness level on Pyramyd Air’s product page to 4. But now she can hear that the Octane is clearly a 3. I apologize to everyone who was mislead by my earlier report. The Octane is a normal-sounding breakbarrel air rifle.
Observations thus far.
I said in Part 1 that the Octane holds very well in the hands. The weight is biased forward toward the muzzle, and the stock is slender when the off hand rests. Add the smooth shooting to this, and I think the Octane might surprise us in the accuracy test.
I plan on shooting the rifle at 10 meters with its open sights first. That should give us an idea of which pellets it likes. Then, I’ll mount the scope and shoot those best pellets at 10 meters, again. That does 2 things. First, it confirms the pellets are as good as we think; and second, it allows me time to adjust the scope for the second accuracy test at 25 yards.
by Tom Gaylord, a.k.a. B.B. Pelletier
We’re back to the BSA Scorpion 1200 SE. When we last tested it, we looked at the velocity and discovered this is a 30 foot-pound air rifle. So, its primary purpose is hunting. I thought that meant I should test some heavy .22-caliber pellets, but I also included a middleweight.
This test was done at 50 yards. I never shot the Scorpion indoors at 25 yards because it’s so loud. I went straight from mounting a scope to shooting at 50 yards. As it turned out, that cost me several more shots than normal to get on paper.
I scoped the rifle with the UTG 6-24X56 AP scope with illuminated reticle.
I knew the scope would be right for the Scorpion because BSA PCPs are very accurate. I wanted a lot of power in the scope to compliment the long-range capability. This scope gave me what I was looking for.
The first pellet I tried was the 21-grain Beeman Kodiak. The first group wasn’t good because the wind kicked up just as I fired a couple of the shots. Sure enough, the 10 holes had a horizontal spread. They measure 1.006 inches between centers, which isn’t bad, but I felt this pellet deserved a second chance.
The second group of 10 Kodiaks measures 0.926 inches between centers. Although that isn’t that much smaller than the first group, this group is rounder; and I feel it’s representative of what Kodiaks will do in this rifle.
Eun Jin dome
I said during the velocity testing that the 28.4-grain Eun Jin dome would probably be good if you were seeking the maximum knockdown power at long range. They developed an additional foot-pound of muzzle energy. They’ve never been the most accurate pellets, but in some PCP rifles they do deliver credible accuracy.
Not in the Scorpion 1200 SE, though. The Eun Jin gave a large groups with a pronounced vertical spread. It measures 1.488 inches between centers and was the largest group of the test. I don’t recommend this pellet in the Scorpion 1200 SE.
JSB Exact Jumbo Heavy, 18.1 grains
Next, I tried the JSB Exact Jumbo Heavy domed pellet. This one is between the medium-weight JSB Jumbo and the heavier Beeman Kodiak, so it gives better velocity with some good power retention. If it shoots at least as well as the Kodiak, it would be worth choosing.
But it doesn’t just shoot better — it shoots WAY better than the Kodiak in the Scorpion 1200 SE. Ten pellets made a group that measures 0.792 inches between centers. The group is very round, as you can see, so we know this pellet is a keeper!
JSB Exact Jumbo 15.9 grains
The last pellet I tried was the 15.9-grain JSB Exact Jumbo. Sometimes this pellet is the best in a PCP rifle, so it had to be tried. This time, however, was not one of those times. Ten pellets made a 1.332-inch group that was not as tight as the Kodiaks or the 18.1-grain Exact Jumbo Heavys. And no wind caused the horizontal spread of these pellets.
The BSA Scorpion 1200 SE certainly has the power and accuracy needed to be a good hunting rifle. I like the way the stock balances in my hands when shooting, as it’s heavy at the muzzle. I don’t care for the fact that it needs 232 bar of fill pressure because that drains even a carbon fiber tank quicker than a 200 bar fill. It does, however, get a reasonable number of powerful shots per fill (25).
The 10-shot magazine is flawlessly reliable. There was never a misfeed in the entire test. And the magazine is below the top of the receiver, so it never interferes with the scope. The trigger is light enough, but I don’t care for the stage 2 creep that I found impossible to adjust out.
I would recommend this rifle to all who like its looks and features.
by Tom Gaylord, a.k.a. B.B. Pelletier
This test is being done because in Part 3, the accuracy test, I felt the scope I was using wasn’t giving the Hatsan AT P1 PCP air pistol the best chance for success. It was a vintage Weaver K856, which means a fixed 8x magnification with a 56mm objective lens. Though it doesn’t say anywhere on the scope, I’m pretty sure the scope’s parallax is fixed at 100 yards. At the 25 yards I was shooting, the target was slightly blurry.
The best group I got in that test was five Crosman Premiers into 0.678 inches at 25 yards. That was shooting off a sandbag rest with a rifle scope.
I said at the end of that report that I would return with a different scope mounted and try again, and today is a report on how that went. The scope I selected this time was the UTG 3-9X40 AO True Hunter that hasn’t hit the market yet. It’s a full-sized rifle scope with a suggested retail price of $104.97, so I would expect to see it sell for something less than that. I’m not going to report on this scope in detail today, but you do need to know that it’s a fine scope for this test. The parallax adjustment worked perfectly, and I was able to get the target bulls into sharp focus. The way I had to hold the pistol to use the scope was a detractor, but it’s no reflection on the quality of the scope, itself. I plan to do a full report on just the scope, but I’ll mount it on one of my rifles of known accuracy.
As I reported, the Hatsan pistol has a proprietary quick-disconnect fill probe that isn’t compatible with other airguns outside the Hatsan line, so I attached it to the hose on my Hill pump. I need my carbon fiber tank for filling all my other PCPs that are universally compatible with the Foster-type quick-disconnect fittings, so the Hill was dedicated to this pistol. It took 26 pump strokes to fill the pistol after 10 shots were fired. That’s 2.6 pump strokes per shot. I said in the last report that the gun seems to give the best results with 7 shots per fill; but since the clip holds 10 pellets, I shot it 10 times per fill. All of today’s groups are 10-shot groups at 25 yards. I feel that’s only reasonable because nobody wants to stop shooting and fill their gun in the middle of a clip.
Shooting was off a sandbag rest, which is fine for a PCP. This pistol does recoil a little when it fires, but that’s well after the pellet has left the muzzle of the gun. The recoil is more of a rocket-like push than a typical firearm recoil, and it’s far from the violent jump of most spring guns.
I overfilled the pistol the first time. I couldn’t clearly see the gauge on the pump and wound up putting 3,500 psi into the gun, rather than 3,000. So, just this one time, I shot 20 rounds on a fill instead of just 10. Had my groups been great, I would have gone back to the chronograph and looked at the velocity again with a 3,500 psi fill.
The Hill pump is great because it allows for such a fill. Other hand pumps peak at 3,000, but the Hill keeps right on going to 3,500. I bought it from Compasseco (which is now owned by Pyramyd Air) years ago when I was testing several BSA and BSA-made derivative PCPs because they’re all pressurized to 3,350 psi.
JSB Exact Jumbo Heavys
The first group fired was 10 JSB Exact 18.1-grain Jumbo Heavy domes. The scope was not sighted in, and the group landed about 4 inches below the aim point and 2 inches to the right. It measures 0.844 inches between centers. While that’s not much better than good, it beats all but 1 of the groups I made with the gun the last time at the range. Since this was 10 shots and not 5 or 7, I have to say that I did measurably better with the new scope.
Since the built-in pressure gauge said there was still about 180 bar left in the pistol after the first group, I loaded the clip with another 10 JSB Jumbo Heavys and shot again. Before shooting, I adjusted the scope through rough guesswork and managed to hit the lower right quarter of the bull at which I was aiming. I really like how well the new UTG scope adjusts, and I like how the knobs can be locked after every adjustment.
This is significant. It means there are more than the 7 shots per fill that I reported in Part 3. But I had to overfill the gun to get the other shots. More on that thought at the end of the report.
Please note that the largest of these 2 groups was 1.053 inches for 10 shots. In the previous test, the 10-shot group fired with the lighter JSB Exact 15.9-grain Jumbos was 2.093 inches. This one is a good four-tenths of an inch smaller. I think that is good evidence that the scope is the big difference this time; and if there’s a secondary difference, it’s that I am learning to shoot this pistol. However, I didn’t shoot this 18.1-grain JSB before, so my comparison isn’t perfect.
The trigger-pull was extremely long and mushy as the pistol came from the box, and it does not help the groups one bit. It’s hard to hold steady when pulling through a long, heavy trigger-pull. Also, I have to hold the end of the scope with my left hand to keep the spacing for my eye so I can see through it. If I were to try to freehand it, I would never be able to see through the scope because the image would keep blacking out with small movements of my eye and hand. So, the hold is both difficult and uncomfortable. A pistol scope would be better, though I doubt the groups would get any smaller with one.
The trigger is adjustable, however, and this is one of those rare instances in which the adjustments really work! I adjusted the long pull in my office after the range and got the trigger breaking fairly crisp and quite a bit lighter. This might have helped the groups by some amount.
I’ve tried adjusting this Quattro trigger in some Hatsan spring rifles before and didn’t see as much improvement; but, of course, in a PCP the trigger isn’t holding such a heavy spring.
Next, I filled the pistol to 3,000 psi and loaded 10 Beeman Kodiaks. This time I thought I had it right until the two final shots. Shots 9 and 10 went high and right from the main group. Eight shots went into 0.701 inches, but the last 2 shots opened the group to 1.118 inches.
This group sort of reminded me that 10 shots were too much for the AT P1 pistol on a 3,000 psi fill, even at 25 yards. Eight seemed to be the maximum with the new UTG scope. But there was one more pellet to try.
I took Skenco New Boy Seniors along, but they’re too long for the Hatsan’s clip. They protrude and don’t allow the clip to turn when the gun is cocked. The only other pellet I had to try was the Crosman Premier.
Once more, I got 8 shots in a smaller group that measured 0.791 inches, then shots 9 and 10 went wide and opened it to 1.266 inches. One went to the left and the other went right, as though I was throwing curve balls. I couldn’t see the pellets in flight; but when I saw the hole each one made, it came as a surprise.
Ten Crosman Premiers went into 1.266 inches at 25 yards from a rest. The first 8 shots went into 0.701 inches, and shots 9 and 10 went wide right and wide left. Once again, 8 shots were relatively close with 2 fliers.
Based on all this data, I’m going to say there are only 8 good shots per fill in this pistol with a 3,000 psi fill. Given the results of both days on the range, I believe I can safely make that statement. But since I was able to fill the pistol to greater pressure and get additional good shots, I think it might respond well to a fill pressure of 3,200 psi and be able to shoot all 10 shots.
The Beeman Kodiaks and Crosman Premiers seem to be the best 2 pellets in this pistol. Next time, I might try a third pellet that hasn’t been tried…like the JSB Exact RS.
Not done yet
I’m not yet finished with the Hatsan AT P1 pistol. In the next test, which I think will be the final one, I’ll try filling to 3,200 psi to see if I can get 10 good shots on one fill. If that doesn’t work, I’ll go back to the 3,000 psi fill and only shoot 8 shots per group. Now that I have a good scope, 2 good pellets, a knowledge of the power curve and fill pressure limits, plus a newly adjusted trigger, I think I can make the gun perform at its best.
Why am I willing to do all this testing? Because there aren’t that many good PCP air pistols available, and I think this might be a good one once I learn all its secrets. I owe you readers that much because so many of you are considering this one.
by Tom Gaylord, a.k.a. B.B. Pelletier
This is the summary report in this series. I’ll give you my thoughts on how this test went, and I expect you to comment, as well.
Three barrels were used in this test. One was the factory barrel that comes with the .22-caliber AirForce Talon SS. It’s a 12-inch Lothar Walther barrel that has a choke of about a half-thousandth inch reduction in the bore diameter for the final 2 inches of length. That makes all the pellets of uniform size as they leave the muzzle, and it may potentially stop any in-bore wobble. This barrel has the standard airgun twist rate of 1-turn-in-16-inches of bore travel, written as 1:16″.
The other 2 barrels were made by Dennis Quackenbush. Neither barrel is choked. One is a 1:12″ twist; the other is a 1:22″ twist. They’re also about 12-inches long and are held in the gun by AirForce Talon SS barrel bushings. Several comments have suggested that because these barrels are different than the Lothar Walther barrel, this test is somehow not fair. But the results of all the shooting prove otherwise. Sure, there are variations from barrel to barrel, depending on the power used and which pellet was shot. But the results are so close between all 3 barrels that whatever differences there might be are overridden by the similarities. In other words, I’m suggesting that if Lothar Walther had made all 3 barrels, there would be similar differences.
The 3 barrels used in the test. Factory barrel in the middle.
I believe the twist rates are what drive the results. We weren’t searching for the most accurate barrel in this test. We were looking for behavior changes as conditions were changed. And we got that.
The first thing that was tested was velocity. Both pellets — the 14.3-grain Crosman Premiers and the 15.9-grain JSB Exact Jumbo were shot from all 3 barrels at each of 3 predetermined power settings. These settings were marked on the gun so they were kept constant throughout the test.
The power settings were the power indicator screw all the way to the left (the lowest setting), and the power screw centered on each mark (settings 6 and 10).
I reviewed the velocity for you in Part 8. Here’s a summary of that report.
In all cases, the velocity increased the most between power setting zero and setting 6. The velocity increase from setting 6 to setting 10 was always smaller than the increase from setting zero to setting 6, and that’s irrespective of the twist rate or which pellet was shot.
What you’re seeing here is the slowing down of the rate of velocity increase as the air flow increases. That’ll become clear in a moment when I discuss the rifle’s maximum velocity potential.
As the twist rate slowed (1:22″ is slower than 1:12″), the velocity increased at most power settings with most pellets. There was one instance with the 1:22″ barrel when the JSB Exact pellet actually went 2 f.p.s. slower at setting 10 than at setting 6; but with all other barrels and pellets, there was always a velocity increase as the power setting went higher.
Focusing on the 1:22″ barrel for a moment, we see that the velocity increases between setting 6 and setting 10 were not as great as they were in either the factory (1:16″) barrel or the 1:12″ barrel. This suggests what we have suspected all along — that the twist rate of the barrel does slow down the pellet as it gets tighter. And we can see from this test that the phenomenon is most apparent at the lower power settings. At the higher power settings, the differences seem to shrink, indicating that the influence of the power setting is overriding the influence of the twist rate. I believe this is an important finding, and it sets up the next observation, which is that the top velocity of the gun was fairly close for all 3 barrels, regardless of the twist rate. The type of pellet made more difference to the top velocity than the barrel twist rate did.
It should be obvious from these results that the Talon SS powerplant has upper limits that cannot be exceeded by forcing more compressed air through the barrel. This illustrates the relationship between barrel length and velocity in a pneumatic airgun.
A second thing I found interesting is that power setting 6 is very close in performance to power setting 10. In the case of the 1:22″ twist barrel, it’s remarkably close…but it’s close for all three barrels. A prudent airgunner might consider this when setting the power wheel adjustment on his Talon SS, knowing that a lower setting uses less air, yet gives velocity that isn’t that much slower.
A third thing is that the velocity performance of the 1:22″ barrel is so good at power setting 6 that it makes power setting 10 useless. Take that thought just a little farther, and you’ll see that all power settings above setting 10 are pretty much a waste of air in a Talon SS with a 12-inch barrel, regardless of which pellet you use.
Next, I tested all 3 barrels with both pellets shot at all 3 power levels at 10 meters (11 yards) and 25 yards. Following that, I tested all 3 barrels and both pellets, again, at 50 yards, only I didn’t use the zero power setting. This was where my eyes were opened regarding the effects of twist rate.
I analyzed the accuracy in 2 different reports. One (Part 9) was the 10-meter and 25-yard accuracy and the other (Part 12) was the 50-yard accuracy, alone. Now, with the table above we can combine these results and analyze all the accuracy data together.
The first observation I’ll make is that at 10 meters, I got 10-shot groups that ranged from as small as 0.092 inches to as large as 0.578 inches. The factory barrel gave the best results with the JSB pellet; but with the Premier, it was the 1:22-inch twist that did the best. Curiously, that pellet and twist rate didn’t seem to change that much as the power was increased (at 10 meters). With all other barrels and pellets, the group size did change a lot as the power changed.
It’s too simple to say the factory barrel with the 1:16-inch twist rate is the best; but of the 3 twist rates in this test, it certainly is the most flexible across the board. However, you’ll notice that the 1:12-inch twist barrel did shoot the best single group (with JSB Exact pellets) at 50 yards. That group is so close to the Crosman Premier group shot by the 1:16-inch barrel that I can’t call a clear winner — BUT — here is what I CAN say. The Quackenbush 1:12-inch twist barrel is certainly capable of shooting 50-yard groups at least as tight as those shot by the Lother Walther barrel; and in my mind, that puts the barrel-equivalency question to rest.
Another observation is that the 1:22-inch twist barrel was just as good at 10 meters as the other 2 barrels, in general, but look at how the groups opened at 50 yards! That says something very strong about the relationship of the twist rate to accuracy. And it also brings up a second observation.
Premier pellets and JSB pellets performed differently throughout this test. Just look at the 50-yard results for Premiers and JSBs with the 1:12-inch twist barrel, and you’ll see what I mean. This is one more bit of evidence that barrels have preferences for certain pellets.
This will be my final remark in this series of reports, and it does not come from the data collected in this test but from the 5-part test of the Diana model 25 smoothbore. In that test, we saw that the smoothbore was able to place 10 JSB Exact RS pellets into a group measuring 0.337 inches at 10 meters. However, at 25 yards, the same pellet loaded the same way made a group that measured 3.168 inches. That difference tells us clearly that spin and not aerodynamic drag is the main key to pellet accuracy. I think we now see that twist rates do matter a lot, and the standard rate is the best all-around rate for now.
At 10 meters, 10 JSB Exact RS pellets made this 0.337-inch group.
At 25 yards, the same JWB-Exact-RS pellets, seated to the same depth, made this 3.168-inch group. They are clearly not accurate after 10 meters.
by Tom Gaylord, a.k.a. B.B. Pelletier
Today, we’ll look at the performance of the Hatsan AT P1 PCP air pistol for accuracy at 25 yards. It took a long time between this test and the last one because this gun is too loud to discharge inside the house. I had to do it for the velocity test and my ears are still ringing. I waited for a day at the range to test the gun for accuracy.
I mounted a vintage Weaver K-856 scope on the gun for this test. It’s a fixed 8x scope with a 56mm objective lens. I thought it would be clear enough at 25 yards (parallax set for 100 yards), but it turned out to be fuzzy. I will change scopes for the next test.
Before I left the house, I filled the gun to 3,000 psi with the Hill pump. You may remember that this pistol has a proprietary Hatsan fill probe, and I wanted to install it on something I could leave it on for a while. My carbon fiber tank is too busy with other guns, so I dedicated the Hill for this job. Because the AT P1 has such a small reservoir, I felt it would be okay to fill the pistol this way. This is the problem with proprietary fill couplings — they have to be installed on something, making it impossible to use that fill device for your other pneumatic guns that have universal Foster fittings.
After filling the gun, I looked at the Hatsan tank gauge. It read about 50 bar, even though I had just put in 206 bar. I knew it was full, so I left it alone. The next morning, the gauge needle was up to 100 bar, but it never did read correctly. That caused a problem at the range when I shot the gun down too far. It was then that I learned that the gauge needle bears no relation to how much air is in the tank.
I started out shooting a group of 5 Crosman Premiers. The first shot landed a quarter-inch below the next 4. The total group size was 0.678 inches, but 4 of those shots went into 0.322 inches. As it turned out, that was the best group of the day.
The trigger-pull was both too long and too heavy for the best in precision. I can normally work around almost anything, but this time the trigger-pull was a real hinderance to good shooting.
I shot the next 5 Premiers at a fresh target after adjusting the scope down. This time, 5 shots went into 0.993 inches, which is considerably larger than the first group. It alerted me to the fact that there may not be 10 good shots on a charge of air.
The pressure gauge on the gun now reads about 180 bar, so I thought there were another 10 good shots in the gun. It wasn’t until later that I discovered the gauge doesn’t read the pressure correctly.
The next 10 shots were JSB Exact 15.9-grain Jumbos. They landed in a group measuring 2.093 inches between centers. That certainly isn’t a good group — especially for just 25 yards. This group has too many shots and was shot with too little air pressure in the tank, but even then the shots are so scattered that I doubt it’s the right pellet for this pistol. But because I don’t know that for sure, I’ll try this pellet again in the next test.
I filled the tank again and changed to Beeman Kodiaks. This time, 10 pellets went into a group measuring 1.464 inches. The last shot went far to the left of the main group. Because it landed in the white, I was able to see it hit the paper. That was the tip-off that 10 shots were too many — even at only 25 yards.
I’d wanted to shoot 10-shot groups, but the AT P1 doesn’t seem to have enough air for 10 good shots on a single charge. According to the chronograph testing I did on Part 2, it has air for about 7 shots, so I limited the next groups to that.
The learning curve this day was too steep for me to be satisfied with these results. I’d lost my edge toward the end of the session, and it wasn’t worth pushing on. I’ll return for a second try at 25 yards with different pellets. And I’ll give those JSB Jumbos a second chance. If I can’t do a lot better than this, I won’t bother trying to shoot the pistol at 50 yards.
The trigger-pull on the AT P1 pistol is too long and heavy for the best accuracy. Also, the scope needs to be changed to give the pistol its best chance to do well. Hopefully, I’ll be able to find another good pellet next time and these problems will disappear. As powerful as this air pistol is, it’ll make a good hunting airgun if it can hit what it shoots at.
by Tom Gaylord, a.k.a. B.B. Pelletier
Today, I’ll report on the final test in this series. This isn’t the final report — just the final test, which is the barrel with the 1:12″ twist, shooting at 50 yards. Get ready to be surprised. I know I was!
I did this test on the same perfect day as the factory barrel that was reported last week in Part 10, and the weather was perfect most of the time. From time to time, there was a very slight breeze that I waited out before shooting. The shooting conditions were as good as they get.
I used the same two pellets we’ve been shooting all along, and they were shot at power settings 6 and 10…just like the other 2 barrels that went before. The gun was shot while resting on a sandbag that’s very stable. When the tank was filled or the power was changed, I always shot one shot to settle the valve. Experience tells me that’s all that’s needed.
The tank was filled to 3,000 psi.
Power setting 10
I first shot both pellets on power setting 10. And 14.3-grain Crosman Premiers were hitting low and to the left. One of them only nicked the target paper, so I photographed the target before taking it off the backer paper, so you could see the complete group.
Here are the two 10-shot groups of Premiers. Notice that they’re hitting to the right of the aim point, which is the center of the bull they touch. The group shot on power setting 10 is at the top, and it shows why I like to use backer paper when shooting at 50 yards.
Then it was time to test the 15.9-grain JSB Exact Jumbo 15.9-grain pellet on power setting 10. This is where the surprise comes! Ten pellets made a 1.259-inch group! If you check back with the results the factory barrel gave, you’ll see that this group is very close to the best group made by the factory barrel (1.153″ for 10 shots with the same JSB pellet on power setting 6), and it’s equal to the group that was shot on power setting 10 (1.283″). This addresses a question many of have had from the beginning of this test — namely, are the Quackenbush barrels equal to the Lothar Walther barrel?
With so little data, it’s impossible to say if these two barrels are exactly as good, but what we now can say is that one of the Quackenbush barrels gave some groups that are at least equivalent to those from the factory barrel. The difference is so small that it might be due to the twist rate rather than the quality of the barrels. That was the position I took at the start of the test, and I think this demonstrates it was valid.
Power setting 6
Next, it was time to test the 1:12″ barrel on power setting 6. Ten Premiers went into 2.234 inches, which is only slightly smaller than the same pellet on power setting 10. As before, the pellet stuck the target low and to the right.
It’s official — the 1:12″ barrel does not like Crosman Premiers out at 50 yards. But that wasn’t the only pellet in this test.
With JSB Exact Jumbo 15.9-grain domes, the barrel did nearly as good on power setting 6 as it did on setting 10. Ten pellets made a 1.363-inch group. Like the Premiers, the JSBs also performed about the same on setting 6 as on setting 10. But that’s not the real lesson. The real thing to note is that the 1:12″ twist barrel was not as good at 25 yards as the factory barrel, yet at 50 yards it almost caught up. In other words, the accuracy of the factory barrel degraded faster as the distance increased than the barrel with the faster twist.
What has been learned?
This is not the final report. I’ll add these results to the previous summary report given in Part 9, and we’ll be able to see all 3 barrels at all 3 distances with both pellets at all 3 power levels. But if I had to give a quick analysis, I’d say the 1:12″ twist barrel surprised me at 50 yards by being better than I expected. At least it was better with the JSB pellets.
And that fact alone — that a barrel can be so much better with one pellet than with another — is good to know. This test has demonstrated that principle beyond all doubt.
A lot more testing needs to be done to thoroughly see all the relationships, but I’ll tell you what I know in the next report, which will be the final report for this series. I think we can advance our knowledge of how pellets perform by quite a bit by combining the results of this lengthy test, the smoothbore test and the pellet velocity versus accuracy test. We’ve been exploring this theme for nearly 2 full years now, and I think we’ve learned a lot!