VALUE FOR MONEY
The redesigned JSB Exact Jumbo Monster 25.39 grain pellets featured in this review are a heavy hunting pellet for use, primarily, with high powered PCP air rifles.
At a typical online Street Price of $11.99 for a tin of 200, these Jumbo Monsters cost 5.96 cents each. This is expensive for a .22 caliber pellet, but you do get a lot of lead in every one. And, hunters shoot relatively few pellets, so it makes sense to go for quality in an airgun hunting pellet.
Of course, leading online retailers offer “buy four tins, get one free” promotions, so the actual price per pellet you pay may be less.
BUY FROM PYRAMYD AIR
JSB Match Diabolo Exact Jumbo Monster .22 Cal, 25.39 Grains, Domed, 200ct![]()
BUY FROM AIRGUN DEPOT
JSB Jumbo Monster Pellets .22 Cal
TEST DATA SUMMARY
| Price per Pellet | 5.96 cents |
| Most Common Weight | 25.32 Grains 25.63 Grains |
| Pellets at That Common Weight | 8% |
| Variation in Pellet Weight (Smallest to Largest) | 3.21% |
| Most Common Head Diameter | 5.56 mm |
| Pellet at That Common Head Diameter | 88% |
| Variation in Head Diameter (Smallest to Largest) | 0.36% |
| Most Common Length | 8.84 mm |
| Pellets at That Common Length | 30% |
| Variation in Length (Smallest to Largest) | 0.68% |
COMPARISON TO MAKERS CLAIMS
The manufacturer claims that redesigned JSB Exact Jumbo Monster 25.39 grain pellets are packed in tins of 200 pellets. The tin tested by HAM contained 201 pellets.
Claimed weight for these pellets is 25.39 Grains. In HAM testing, we found that the redesigned JSB Exact Jumbo Monster 25.39 grain pellets we tested had an average weight of 25.45 Grains. In fact, 66% of the tested pellets weighed more than the manufacturer’s claimed weight.
JSB claims that redesigned JSB Exact Jumbo Monster 25.39 grain pellets have been designed for use with the most powerful PCP air rifles. HAM agrees with that claim!
CONSISTENCY
No damaged or malformed pellets were found in the tin of redesigned JSB Exact Jumbo Monster 25.39 grain pellets tested by HAM.
Head Diameter consistency was extremely good, as you can see from the chart. No less than 88% of the tested pellets had the same head diameter. In fact this head diameter was 5.56 mm.
The variation in head diameter between the smallest and largest pellets was just 0.36%. This is a very good consistency.
As with other heavy pellets tested by HAM, these redesigned JSB Exact Jumbo Monster 25.39 grain pellets clearly achieve part of their weight though having a head diameter that’s significantly larger than the nominal 5.50 bore of .22 caliber air rifles.
Unfortunately there was significant variation in weight among the redesigned JSB Exact Jumbo Monster 25.39 grain pellets tested by HAM.
Only 8% of the tested pellets had the same weight, at 25.32 Grains, with another 8% at 25.63 Grains. The variation in weight between the lightest and heaviest pellets tested was high at 3.21%. The lightest was 24.94 Grains, while the heaviest turned the scales at no less than 25.74 Grains.
Surprisingly, none of the tested pellets actually weighed the claimed 25.39 Grains!
As always, the redesigned JSB Exact Jumbo Monster 25.39 grain pellets were weighed on HAM’s incredibly precise, laboratory-grade milligram balance.
Consistency was well-maintained with pellet length, however. As you can see from the chart below, 30% of the redesigned JSB Exact Jumbo Monster 25.39 grain pellets had a length of 8.84 mm. The variation between longest and shortest pellets was also well-controlled at just 0.68%
Note that these are long pellets. They do fit into a Benjamin Marauder magazine, for instance. However, it’s possible that they may be too long for others, requiring the use of a single shot tray for loading, if available.
DIRTINESS
The JSB pellets tested to date by HAM have mainly been quite clean. The amount of lead dust and particles that’s inevitable in the production of lead pellets is usually very well controlled.
However, the redesigned JSB Exact Jumbo Monster 25.39 grain pellets tested by HAM were pretty dirty. There was actually a total of 1.59 Grains of lead “junk” in the tin.
However, as you can see from the photograph below, the majority of that was in one relatively large piece of lead swarf. So maybe we just got unlucky there…
DOWNRANGE PERFORMANCE
In HAM testing, the Ballistic Coefficient of redesigned JSB Exact Jumbo Monster 25.39 grain pellets was found to be high at 0.039.
This means that, although these pellets travel relatively slowly due to their weight, they retain a considerable proportion of their energy downrange.
In fact, as the Chairgun chart show, no less than 80% of the initial Muzzle Energy was retained at 37 yards. Even at 59 Yards, the pellet still retained 70% of its initial energy.
Obviously these pellets are waaaay too heavy for real world use in out standard Beeman 1073 test gun. However, the considerable drop in impact point at range will mean that careful use of a scope’s Mildot reticle will be required for accurate shooting, even with the high powered PCPs these pellets are designed for.
HUNTING USE
With such a high Ballistic Coefficient and strong downrange performance, the redesigned JSB Exact Jumbo Monster 25.39 grain pellets are ideal for hunting.
Penetration into the standard HAM ballistic soap block was 45 mm, with a entry hole of 8 mm.
The photograph below shows the fired pellet after removal from the soap block. It’s on the left, an unfired redesigned JSB Exact Jumbo Monster 25.39 grain pellets is on the right.
As you can see, the fired pellet increased in diameter from 5.56 mm to 5.62 mm. Also visible are pronounced rifling marks on the head and skirt of the fired pellet, a result of its oversize diameter.
BUYING AND OWNING
Redesigned JSB Exact Jumbo Monster 25.39 grain pellets are readily available online from the usual suspects!
They are supplied in the usual JSB push top tin with a foam disk under the lid to prevent damage in transit.
Of course, as with all lead airgun pellets, appropriate precautions associated with any lead product must be taken when handling and using these redesigned JSB Exact Jumbo Monster 25.39 grain pellets.
TEST DATA
BUY FROM PYRAMYD AIR
JSB Match Diabolo Exact Jumbo Monster .22 Cal, 25.39 Grains, Domed, 200ct![]()
BUY FROM AIRGUN DEPOT
JSB Jumbo Monster Pellets .22 Cal
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
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.
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