JSB Exact Premium Diabolo 8.44 Grain .177 Cal Pellet Test Review

VALUE FOR MONEY

JSB Exact Premium Diabolo 8.44 Grain pellets are manufactured in the Czech Republic by JSB from soft lead. The shape is a domed diabolo. The MSRP is $14.99 for a pack of 200 pellets.

JSB pellets have a great reputation in the market for quality and consistency. That leads to a high chance of accuracy with many types of air rifle.

At an MSRP of 7.5 cents per pellet, JSB Exact Premium Diabolo 8.44 Grain pellets are expensive, about twice the average MSRP price per pellet of 3.3 cents for .177 caliber lead pellets. However, this is still very cheap compared to the cost of alloy pellets. And these pellets are hand-selected for consistency. with an awesome reputation among precision shooters.

BUY FROM PYRAMYD AIR
JSB Exact Premium Diabolo, .177 Cal, 8.44 Grains, Domed, 200ct

BUY FROM AIRGUN DEPOT
JSB Exact Premium Diabolo 8.44 Gr 200 Ct

TEST DATA SUMMARY

COMPARISON TO MAKERS CLAIMS

The manufacturer claims that JSB Exact Premium Diabolo 8.44 Grain pellets have a weight of 8.44 grains – 0.547 grams, plus or minus 0.001 gram. This is an incredibly tight tolerance range that it nearly – but not quite – matched by the pellets tested by HAM.

In fact, the JSB Exact Premium Diabolo 8.44 Grain pellets tested by HAM showed an average weight of 0.545 grams per pellet. That’s 8.42 Grains.

The head diameter specified on JSB’s website for these pellets is 4.52 mm. The average head diameter of the pellets tested by HAM using a Pelletgage “go, no go” gauge was 4.51 mm. Again very, very close, but not exactly matching the claims.

The manufacturer also claims that 200 pellets are in each pack. And yes, there were exactly 200 pellets in the package tested by HAM.

CONSISTENCY

Of the 200 pellets in the pack of JSB Exact Premium Diabolo 8.44 Grain pellets tested by HAM, there were zero damaged or malformed pellets. This is undoubtedly due to the hand selection and individual packaging into styrofoam trays in a robust clamshell box.

76% of the JSB Exact Premium Diabolo 8.44 Grain pellets tested by HAM had a head diameter of 4.51 mm. 18% of the pellets had a diameter just 0.01 mm smaller, while 6% of the pellets tested showed a head diameter 0.001 mm larger. This is a very consistent distribution of head diameters!

The average weight of the pellets tested by HAM was 8.42 grains. However, interestingly, none of these individual pellets actually had that specific weight!

The JSB Exact Premium Diabolo 8.44 Grain pellets tested by HAM showed a tight distribution of weight. 16% weighed 8.40 grains, 40% weighed 8.41 grains, 0% weighed 8.42 grains, 30% weighed 8.43 grains, while 12% weighed 8.44 grains. There was one outlier (= 2%) where the pellet weighed 8.46 grains.

Pellet length was also very consistent for the JSB Exact Premium Diabolo 8.44 Grain pellets tested by HAM. The most common length was 5.29 mm: 62% of the pellets measured by HAM were of that length. 22% of the pellets were 5.28 mm long and 14% 5.30mm long. Again, there was just one pellet that measured 5.31mm in length, that’s 2% of the 50 pellets measured.

To put things into perspective, 98% of the JSB Exact Premium Diabolo 8.44 Grain pellets tested by HAM were effectively the same length. That’s 5.29 mm. The variation was less than one third of the diameter of an average human hair (0.06 – 0.08 mm)!

DIRTINESS

The JSB Exact Premium Diabolo 8.44 Grain pellets tested by HAM were visually very clean. This was confirmed by washing the pellets and measuring the amount of dirt that was in the packaging.

Measurement showed than there was just 0.093 Grains of dirt per 100 pellets. This is a very low figure. This dirt was photographed on a white cloth, in the photograph below. As you can see, there’s almost nothing there!

DOWNRANGE PERFORMANCE

Downrage performance of JSB Exact Premium Diabolo 8.44 Grain pellets has been charted using the popular ChairGun ballistics program.

This shows that – for the ” nominally 1,000 FPS” standard air rifle used for HAM testing, if sighted-in at 29 yards, the point of impact would be within plus or minus half an inch on the target at all ranges between 12.0 and 42.7 yards.

The Ballistic Coefficient used for these calculations was found in the ChairGun database. It’s 0.0210.

If you prefer to see numbers rather than charts, here’s the data from ChairGun from which this graph was created.

Range   POI     Drift    Time    Vel.    Vel.  Energy  Energy    Drop
(Yard)     (In)      (In)     (sec)   (Ft/s)     (%)  (FtLbf)   (%)        (In)

10     -0.56     -0.20   0.034   846.1    93.7   13.38   87.78    -0.2
15     -0.14     -0.44   0.052   820.6    90.9   12.59   82.57    -0.5
20      0.15     -0.78   0.071   796.8    88.2   11.87   77.85    -0.9
25      0.30     -1.22   0.090   774.4    85.7   11.21   73.52    -1.5
30      0.31     -1.76   0.110   752.8    83.4   10.59   69.49    -2.2
35      0.16     -2.39   0.130   732.2    81.1   10.02   65.73    -3.0
40     -0.14     -3.12   0.151   712.3    78.9    9.48   62.21    -4.1
45     -0.62     -3.96   0.172   693.2    76.8    8.98   58.92    -5.2
50     -1.28     -4.89   0.194   674.8    74.7    8.51   55.83    -6.6
55     -2.13     -5.94   0.216   657.0    72.7    8.07   52.92    -8.2
60     -3.19     -7.09   0.240   639.6    70.8    7.65   50.16    -9.9

HUNTING USE

The Muzzle Energy of the JSB Exact Premium Diabolo 8.44 Grain pellets tested by HAM averaged 15.25 Ft/Lbs. As Muzzle Energy had dropped to just 70% at 30 yards, this should be considered a maximum hunting range for small game in most medium-powered air rifles. Shot placement is likely to be outstanding, if you do your part!

Remember that the JSB Exact Premium Diabolo 8.44 Grain pellet is really a target shooting pellet and not a dedicated hunting round.

HAM tests the penetration of pellets using a standardized bar of soap. A sample JSB Exact Premium Diabolo 8.44 Grain pellet penetrated 47mm into this soap with a straight wound channel, as you can see below. The entry wound had a diameter of 6.0mm. The pellet did not fragment or significantly change shape in the soap block.

BUYING AND OWNING

JSB Exact Premium Diabolo 8.44 Grain pellets are easily available online from the usual sources including Pyramyd Air and Airgun Depot. As you can see, the packaging is exemplary!

As part of this HAM test review, we weigh the total pellet package “as received” and then after washing the pellets. This enables us to discover the amount of lead dust – or dirt – on the pellets.

In the case of the JSB Exact Premium Diabolo 8.44 Grain pellets tested by HAM, the dirtiness of the pellets is just 0.093 grains per 100 pellets. This is extremely low for lead pellets and not much more than that for many types of alloy pellets. This means that these pellets are very clean to handle, even though all appropriate precautions associated with any lead product still must be taken in use.

TEST DATA

For background details on HAM’s Pellet Test Review methodology, check out this link.

Chairgun is a product of Hawke Sports Optics LLC and is used with permission. Check out http://www.hawkeoptics.com

BUY FROM PYRAMYD AIR
JSB Exact Premium Diabolo, .177 Cal, 8.44 Grains, Domed, 200ct

BUY FROM AIRGUN DEPOT
JSB Exact Premium Diabolo 8.44 Gr 200 Ct

Understanding HAM Pellet Awards

HAM Pellet Awards come from the most rigorous, professional and comprehensive pellet testing by any independent publication. They are the result of much precise measurement and analysis using high precision measuring devices and highly-experienced testers.

Note that accuracy is a product of the complete “system” of airgun, scope, atmospheric conditions and shooter ability – not the pellet alone.

This means that no pellet test review can predict the accuracy of a particular pellet with YOUR individual air rifle. That’s why we do not measure accuracy in these pellet tests.

What HAM Pellet Awards do recognize is manufacturing consistency. Inconsistent pellets definitely will be inaccurate, consistent pellets are much more likely to be accurate.

HAM Awards also recognize value. There’s considerable variation in the price of airgun pellets. This means that an 8 cent pellet needs to score higher than a 2 cent pellet to achieve an award.

For full details of the HAM Pellet Award scoring methodology, please check out our Pellet Testing page.

For a full listing of HAM-tested Ballistic Coefficients, please see our Ballistic Coefficients page.

This entire article including scoring, data etc is Copyright Hard Air Magazine and may NOT in part or in whole be reproduced in any electronic or printed medium without prior permission from the publisher.