What’s The Best Slug Weight For My PCP Air Rifle?
What’s the best slug weight for my PCP air rifle? That’s a common question for many airgunners as they start to investigate shooting with this new type of airgun ammo.
Understanding Muzzle Energy
As we discussed in a previous HAM post, airgun slugs tend to be much heavier than conventional lead pellets. For example, in .22 caliber, slug weights range between 20 and 40 Grains. This compares to an average lead pellet weight of about 14.5 Grains in .22 cal.
For best results – shooting between about 850 and 950 FPS – we need to match the slug weight against the power level of your PCP. If you try to shoot a slug that’s too heavy for your gun, it will travel very slowly: you’ll effectively be using a mortar. That’s NOT the desired result!
As slugs are heavy and as PCP air rifles develop their maximum power with the heaviest ammo, all you need to do is find out the maximum power for your air rifle. This is called Muzzle Energy and is expressed in Ft/Lbs.
The chart below shows how the Umarex Gauntlet 2 develops a maximum of 45.43 Ft/Lbs with 25.39 Grain JSB Monster pellets in .22 caliber. Note that this maximum Muzzle Energy is obtained at MINIMUM Muzzle Velocity! Lighter pellets shoot faster, of course, as you can see and would expect.
Let’s Find The Muzzle Energy For My PCP
This is important as – sadly – not all airgun manufacturers tell us the maximum Muzzle Energy of their products. Even now, there are some PCPs out there that are marketed on the basis of the highest attainable Muzzle Velocity. FPS still sells to the uninitiated!
But as this top FPS is always achieved with the lightest pellets, they are actually telling us the minimum Muzzle Energy of which their PCP air rifles are capable. This is of zero value if you are looking to shoot slugs.
In some cases, a maximum Muzzle Energy is listed by the manufacturer, but this may be incorrect – as we will see below…
For this investigation, I did what most enthusiastic airgunners would do. I went to the Pyramyd Air and Airguns of Arizona websites and looked at the PCPs they offer. In total, I found 114 different models of PCP air rifle. Wow we really are spoiled for choice, aren’t we!
Both Pyramyd and AoA are reputable companies that understand airguns. They publish Muzzle Energy specifications for PCPs wherever possible. Below we see the data for the HAM Gold Award-winning Brocock Sniper XR Magnum. But sometimes they simply do not have the information to publish that figure.
For example, one manufacturer publishes the following claim for its new .22 caliber PCP air rifle: “Velocity 900 feet per second using alloy pellets”. OK, but what weight alloy pellets? (They don’t tell us). If we assume that they are the lightest weight possible (in order to reach the highest FPS) at 9.7 Grains, we can calculate a Muzzle Energy for that gun of 17.45 Ft/Lbs.
Now I’m 200% sure that the maximum Muzzle Energy with heavier ammo is going to be North of 20 Ft/Lbs, but by how much? Some serious Googling failed to find the answer. In my personal view, if the manufacturer does not provide a Muzzle Energy specification for their air rifles, they’re not encouraging you to use slugs.
Then there’s another manufacturer with a reputation for building powerful PCPs that – amazingly – does something different but equally unhelpful. When searching for a .22 caliber PCP of their manufacture, I’m presented with the information that this model “easily achieves 105 Ft/Lbs of energy in .25 caliber“. Sure, but what is the power in .22 caliber? Again, multiple Google searches failed to find the answer.
OK, But Tell Me! What’s The Best Slug Weight For My PCP Air Rifle?
In spite of the above issues, I did the best I could with the information available and analyzed the Muzzle Energy data I could find (or deduce) for those 114 PCP air rifles in .22 caliber.
Here’s what I found…
The lowest-powered .22 caliber PCP air rifle currently in the market is the SIG MCX Virtus with a maximum of 12 Ft/Lbs. The highest is the FX Impact M3 with 700mm barrel at 84 Ft/Lbs in its latest version.
The average Muzzle Energy across all 114 models is 35 Ft/Lbs. In reality – due to the “900 FPS with alloy” issue, the real (or corrected) average in .22 caliber will be a little higher. Let’s guess 37 Ft/Lbs.
Here they are.
Now if we go back to our graph of ammo weights and FPS, we can see the Muzzle Energy range that’s required for successful slug shooting in .22 caliber.
This shows that a PCP having a Muzzle Energy of 30 Ft/Lbs could be just powerful enough to shoot the lightest slugs – HAM Gold Award-winning 20.3 Grain Daystate Howlers – at just below the 850 FPS that’s a minimum realistic Muzzle Velocity for slugs.
It also demonstrates that – should you want to shoot 30 Grain slugs – your .22 caliber PCP air rifle will need to produce somewhere between 48 and 61 Ft/Lb of Muzzle Energy.
Now our analysis of models looks like this.
Can These Popular PCPs Shoot Slugs?
Now let’s look at some popular .22 caliber PCPs and see what weight slugs they’re powerful enough to shoot. Note that I didn’t say “shoot accurately”. As with pellets, each gun will have its own preferences for accuracy and any slug may not shoot accurately in your specific air rifle.
Let’s refer to this graph comparing weights and power required. It’s a “zoomed in” version of the one above and works in the same way…
1. Benjamin Marauder
The claimed Muzzle Energy spec of the Marauder is 21 Ft/Lbs. However, this refers only to the .177 caliber model. The correct value for the .22 caliber Marauder is actually 32 Ft/lbs. The HAM test review (one of our first, back in 2014) recorded a maximum Muzzle Energy of 33.4 Ft/Lbs with 21.14 Grain H&N Baracuda Match pellets. So, yes you will be able to shoot Daystate Howler slugs in your .22 caliber Marauder, even if you have to forego the heavier types.
If you upgrade your Marauder with the Archer Airguns Marauder Tune Kit (how’s that for a shameless plug?), you should have enough power to shoot slugs up to about 23 or 24 Grains in weight.
2. Umarex Gauntlet 2
In HAM testing, the .22 caliber Gauntlet 2 achieved a maximum Muzzle Energy of 45 Ft/Lbs. That should be good for slug weights up to 28 Grains. Note that the Gauntlet 30 model shot .30 caliber slugs very accurately in HAM testing.
3. Air Venturi Avenger
The Gold Award-winning Avenger developed a peak Muzzle Energy of 36 Ft/Lbs with HAM’s Full Power Tune. So again slug shooting is possible. In this case ideally with weights between 20 and 22 Grains.
There’s One More Thing
One other issue with slugs is that they tend to grow longer – much loner – with increasing weight. We can see this with the H&N slugs below. Before you rejoice at the heaviest weight slugs your air rifle will shoot, check their length first. Make sure they fit into the magazine. If not, you’re not going to be shooting them at all…
So what’s the best slug weight for my PCP air rifle? If you’re shooting .22 caliber, now you know. All you need is is confirmation of the maximum Muzzle Energy for your specific air rifle.