Airgun slugs: All you need to know

Airgun slugs

There's a whole lot more involved in producing these than I could have possibly imagined. - Credit: Archant

Terry Doe decides he needs to know more about the ever-growing use of airgun slugs in place of traditional pellets, so speaks to the founding fathers Pro Hunter Swaging

Testing airgun slugs

Yvonne puts a batch of test samples downrange. The amount of personal input involved in developing, producing and testing these slugs is nothing short of staggering. - Credit: Archant

I’ve done my share of exploring new airgun technology in the past year or two, but one area has been shamefully neglected, and that’s using slugs. I’ve tried them and they worked well in my go-to rifles, and several of my friends swear by them, but I need to do more exploration for myself, so I called the ‘founding fathers’ of the UK slug movement, Grahame and Yvonne of Pro Hunter Swaging, for some more information. Here’s what Yvonne told me.

Airgun slugs

Ready to fly to another happy customer. - Credit: Archant

‘Pro Hunter Swaging regenerated slugs, introducing them back into circulation in 2019. With us being the first UK company to manufacture hand-swaged slugs, we pride ourselves on having ‘the best’ in quality and consistency, and being at the forefront of this relatively new revolution of air rifle ammunition. Definitely a game-changer to air rifle ammo, we know what is needed to produce a great air rifle slug!

After years of testing slugs, we know how to create them to handle the air rifles of today, from extremely high-powered rifles to sub-12 models. Before we decided to offer these to the general public, we initially made one style of slug, our Premium Standard, then our Premium High Impact was introduced at a later date, to offer an alternative style to our Premium Standard range, and the Premium High Impact range slugs are unique to us. Our Standard range is extremely popular, slightly easier to produce, and are much easier on the pocket, although all our slugs are individually hand swaged for precision and quality. For a full description on both styles, visit our website’

Airgun slugs

The lead cores, prior to the hand-swaging process. Plenty of processing to come, yet! - Credit: Archant

My next question was about slug production, although, understandably, Yvonne and Grahame aren’t able to reveal the process, I learned more than I thought I would. 

‘Our hand-swaging process is time-consuming and intricate, but we know it’s the best way to make a great slug. We have knowledge of how, why and what is needed to meet our standards and those of our customers, and we add the input from those customers to our own 40-odd years of shooting experience. 

Swaging is a non-heat process used to press a lead core into a desired shape under high force, to a pre-formed die shape. At Pro Hunter Swaging all of our slugs are manufactured using this process and we pride ourselves on quality and consistency. We can also monitor the weight consistency of our slugs at regular intervals. It is not as simple as setting up a press and expecting it to produce the same slug every time.

The speed of swaging, and pressure used, play a big role, which can alter the weight of the slug being  produced. This may only be tenths of a grain, but we aim for one tenth of a grain, + or -, and we always strive to produce the most consistent slug possible, and this process does take practice.

Airgun slugs

All of the 'tails' and rejected slugs will be recycled. This lead is far too precious to waste. - Credit: Archant

‘Dies and punches are a critical factor in producing our quality slugs, and ours are machined to our specification to a very high degree of accuracy.  A die or die set is machined to the desired slug shape and diameter, then a top punch presses down into the die compressing a lead core, forming the desired slug shape and base; a base punch also forms the desired hollow point. This will produce a small ‘bleed off’ of lead, called ‘tails’.

Whichever slug we are producing, it is always swaged in the same die set, so there is no variation in batches, unlike mass-produced slugs, which can be the same style of slug, but produced on different machines.

Because every single one of our slugs is individually hand-swaged, any imperfections are easily seen immediately, making our quality control as effective as possible.’

Airgun slugs

Consistent weight is just one crucial factor in the production of Pro Hunter slugs. - Credit: Archant

‘The quality of lead is also a factor not to be overlooked. We source all of our lead from a reputable company that assures a 99.95% purity on every batch. This again is critical for consistency in maintaining weight and performance. We have found that poor lead quality can have a bearing on accuracy as well as appearance.

All of our slugs have to pass our rigorous testing process before they go on sale and any that have not passed our quality control, and bleed-offs (tails) from the swaging process, are recycled and turned into new slugs to minimise waste. Again, this all is done by hand.’

Airgun slugs

After the intensive production process, it's no surprise to find that the Pro Hunter slugs are well protected. - Credit: Archant

When deciding to make a new slug, a lot of factors and considerations are essential. You cannot expect all grain weights to work well. As slugs rely on ‘spin stabilisation’, the weight, shape, hollow and base all have an influence on whether they will work or not. This means it can take months to produce a slug that meets our standards.

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As you have probably noticed, we produce certain grain weights for this reason only, and are always testing for new slugs in all calibres. Pro Hunter Swaging will never sell a slug that we have not tested, or that we are not satisfied with its performance. As I said earlier, we also act on our customers’ feedback, and thank all those who do take the time to get back to us.’