Gary Wain investigates: bent pellets

Responding to the request of an Airgun World reader, Gary examines the effects of deformed pellets

Flipping through a past issue of Airgun World, my eye was drawn to my out of place, ugly mug in the Letters pages. Reader Keith Wallace wondered what the effect of external influences are on our ability to shoot accurately and suggested I might like to examine the effect of pellet deformation on accuracy.

I thought it was a great idea.

So what are we talking about when we say ‘pellet deformation’? Well, I’m sure you’ve all experienced that feeling when you open a new tin of pellets to find a great many have been damaged.

Likewise, you’ll have experienced the ‘flyer’, the shot you know was well aimed, only for it to go wide of the mark. Was it you, or the pellet?

Fit to shoot

Before embarking on this project, I first had to define exactly what I would be testing and how I would do it. I decided to test both .177 and .22, and to use chiefly round-headed pellets because it’s those that are favoured both for hunting and on the HFT/FT circuit.

As an aside, I thought I’d also see what the effects of deformation were on wadcutter-type pellets in .177. I reasoned that in order to provide a degree of consistency, rather than just firing already deformed pellets, I would actually inflict varying degrees of damage to the pellet skirts and the heads.

So many questions were buzzing around in my head. Would the damage have any effect? If it did, how large would this effect be? Would it be more pronounced on a certain calibre? Would it be enough to cause the flyers we see, or do we have to look elsewhere for our inaccuracies? I was more than a bit excited to find out.

We know not all pellets will work well in all guns as the barrels aren’t the same. So having recently taken delivery of a Daystate Pulsar, the first thing I had to do was to find a brand of pellet that worked well with the gun. Like many, I’ve got a good few tins of pellets knocking about the place, but not enough to give me a large enough cross-section of the available brands.

Thankfully, having had a chat with Trevor Horner – ‘The Chair Man’ at the Northern Shooting Show – when he was representing Idleback’s South Yorkshire Shooting Club, I remembered he sold a range of top-branded domed pellets in both .177 and .22, which are intended for accuracy testing. The pellets come in individual packs of 20. The packs are mounted on a card, listing not only the brand with a picture of the tin, but the ballistic coefficient of each make of pellet. ‘Just the thing I’m looking for’, I thought and so a few days later I was good to go with a range of pellets for testing.

Time to bend ‘em

Having decided upon a pellet, I shot groups of five shots at both 20m and 35m (realistic hunting distances). For the wadcutters, I shot at 10 metres, the distance at which the discipline is shot. The steely-eyed match target shooters will notice I’ve used a Feinwerkbau 601 for the 10m testing. This is my old rifle I used many moons ago so I know exactly which brand of pellets it loves, and how devastatingly accurate it is.

Having progressed to a point where I was happy with the grouping of all rifle and pellet combinations, I set about deforming the pellets. I decided I’d deform them in a variety of ways, in groups of five. That way, I could assess the effects of the damage in an incremental way.

The first batch of five merely received a pronounced inward ‘lipping’ of the skirt’, similar to that seen when pellets get damaged in the tin, but a bit more so. The second batch received a double-lipping, with opposing sides of the skirts being bent inward. The third batch must have wondered what they ever did wrong because I went totally postal on them, completely crushing the skirts. For the fourth batch, I decided to move away from the skirts and deeply score the pellet heads with a knife, giving them some duelling scars to remember me by.

Results

In total, I tested both .22 and .177 domed at 20 and 35 yards, and the wadcutter .177 at 10 metres. I have to say, the results were far from what I expected. With the domed pellets, I was pretty sure lipping the skirt would have a pronounced effect and that double-lipping or crushing the skirt would be disastrous to the accuracy of the pellet. I also conjectured that scoring the head of the pellet would have very little detrimental effect.

With regard to the .177 wadcutters at 10m, I was convinced even the slightest mark would send the pellet way off target. I should have learned from my previous testing experiences that the results garnered can often be far from what were expected.

In conducting the pellet testing stage, I noticed some makes of pellets had thinner-walled skirts than others and so were more susceptible to damage in the tin, or indeed, at the loading stage. I’m familiar with the school of thought suggesting the damage caused to those with thinner skirts would actually ‘reform’ in the barrel, so as a little side test I took some of the thinner-walled and thicker-walled pellets and fired them into a bucket of water with sponge in the bottom to see if indeed this was true. Guess what, they don’t reform, they stay exactly the same.

I found that with the domed pellets in both calibres at 20m, there’s no discernible effect on the accuracy of the pellet in all tests, other than the pellet head scoring. Even then, the variance was negligible.

Out at 35m, there was a more pronounced effect on the accuracy of the pellets with their heads scored (top-left in the target images). Lipping the pellet skirt (top-right images) had very little effect on accuracy, and in fact double-lipping the skirt (bottom-left images) bizarrely, actually seemed to improve it.

The one thing though that did have a pronounced effect on accuracy was totally crushing the pellet’s skirt, but I have to say, nothing like as bad as I was expecting.

The wadcutters at 10m mimicked the results of the roundheads, even to the point where the double-lipped pellets presented a smaller group size than the control (bottom-left). Crushing the skirt of the pellet (bottom-right) enlarged the group and caused a flyer, as it did with the domed pellets and also moved the POI up and left.

Final thoughts

Well, as an ex-10m match target shooter, I’ve learned I probably didn’t need to spend hours selecting totally undamaged, perfect pellets, other than for the confidence of knowing every facet of my hardware is the best it can be,

When it comes to the domed pellets, at 20m with group sizes only varying by a millimetre or two, there’s no real difference between a perfectly formed pellet and a massively damaged one.

Out at 35m, there is an observable effect. But remember, I really massacred these pellets way beyond the slight damage you see in a tin.

From now on, if I fire a slightly lipped pellet from the tin and it goes wide of the mark, I’ll have to look to my technique rather than blame the pellets. In the meantime, now I need to amend my big fat book of shooters’ excuses!

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