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JSB Exact Premium Diabolo .177

Mike Morton tests the JSB Exact Premium to see whether this top-class outdoor competition pellet is worth a premium price

JSB Exact Premium Diabolo .177

It may be tempting to look back with rose-tinted glasses at the airguns, scopes and other shooting paraphernalia of yesteryear, but I firmly believe that in terms of airgun ammunition we’ve never had it so good. Pellet quality, at least from the major manufacturers, really is first-rate, with some of the very best in the world coming from JSB. But if you really want the ultimate, then JSB has gone one step further with the Exact Premium Diabolo.

These pellets are available in .177 and are sold in a plastic box of 200. The box has a proper hinged lid, and the pellets are nestled within two trays made of polystyrene, each containing 100 projectiles. It can be hard to grab an individual pellet, especially in this calibre, but each Exact Premium sits head-down in a shallow recess, making it easy to extract them by the skirt.

They’re not cheap, coming in at around £15.95 per box, but the big selling point apart from the packaging is the fact that they are ‘carefully selected, one by one’ to ensure a consistent weight, which is advertised at 8.44 gr, with this consistency being vitally important to accuracy.

Mike’s scales only measure to one decimal point, but the sample of 50 pellets that he weighed all came in at 8.4gr

The pellets I bought for this test have a head size of 4.52mm, which I’ve found to be a good match for several of my .177 rifles. They look like regular JSB Exacts, the difference being the extra attention paid to sorting them by weight. I’ve had excellent results with regular Exacts, Exact Express and Exact-derived pellets made for other companies, and wondered whether these premium-priced projectiles would deliver anything more than their more common counterparts.

JSB explains that these pellets weigh 8.44 gr, or 0.54g, with each pellet’s weight being accurate to 0.001g. My digital scales are nowhere near accurate enough to measure to this level of finesse, but I did put my usual sample of 50 onto the scales and got a recorded weight of 8.4gr for each one. So far, so good.


JSB Exact Premium – key specs

Pellet: Exact Premium Diabolo
Manufacturer: JSB (
Type: Weight-sorted domehead diabolo
Calibre: .177
Head size: 4.52mm
Length: 5.97mm
Supplied in: Box of 200
Price: £15.95
Advertised weight: 8.44 gr
Measured weight: 8.40 gr
Uses: Target shooting, hunting, precision plinking


Test Conditions

I include a small report on the test conditions usually to comment about any wind, if present. However, this particular test was carried out in the bitterly cold sub-zero temperatures that we experienced just before Christmas. 

I carried out this test over two days, with my car registering -5 °C each day. I think this must have been the coldest weather that I’ve ever shot in. In these icy conditions, I was decidedly uncomfortable, and so was one very important piece of equipment, but on the plus side at least there was good visibility and absolutely no wind.



I started the test with two rifles, one unregulated, the other being my electronic Daystate Red Wolf. I won’t name the unregulated rifle, as other unregged airguns might well have behaved the same in these extremely cold conditions, but this normally accurate rifle was shooting all over the place, so it was ruled out in favour of the Wolf.

It’s not the end of the world, but I have no velocity data this time round because the chronograph also refused to function properly in the cold. I assumed it was the battery, and tried warming it in my hands, and even came back having bought a brand new battery, but it seems the electronics in the device itself couldn’t cope with the cold. The Red Wolf, on the other hand, despite being electronic itself, didn’t miss a beat and was as accurate as ever.

These pellets are clearly geared towards the HFT and FT shooter, so I was happy to carry out this test at my normal distances of 20, 30 and 40 yards, with the rifle zeroed at 30. At 20 yards the JSB Exact Premium and Red Wolf combo delivered a five-shot group measuring 2.4mm centre-to-centre, with me applying 5mm of holdunder.

At the zero distance of 30 yards, group size was a tiny 3.7mm centre-to-centre, with me aiming on, while back at 40 yards it was 8.5mm centre-to centre, with 15mm of holdover. If you look closely you’ll see this was a six-shot group, as I miscounted. I blame the cold.

Regardless of the missing chrono data, these pellets delivered premium results. Are they worth the extra? Well, I suppose you could get the same by sorting a tin of 500 by weight. But that’s a long job that’s been done for you here. 


JSB Exact Premium Diabolo pellets do everything you’d expect of them, so if you want pre-sorted ammo to help give you the edge in your chosen shoot, it’s worth giving them a go