Compromises are often an integral part of buying a new air rifle. Your customers might settle for a gun while wishing it was a bit more compact or had a higher shot count. Modular air rifles can solve these issues. 

If a wide range of components are available, there are two primary benefits. One is that manufacturers can very quickly adjust assembly if they see a particular configuration trending. Secondly, and more importantly, the customers can buy a gun that is close to what they want and add specific components to perfectly suit their individual needs.

For a meaningful modular design, certain criteria must be met. For instance, a wide range of components should be available and accessible to the end user. And the parts must be reasonably priced, and the average customer should be able to install them.

Component Options

The types of components that a modular design offers can vary, but a selection of barrels of different lengths, calibers and twist rates is a good starting point. For instance, some modular rifles offer a barrel with the length and twist rate to optimize performance with airgun slugs rather than conventional pellets. Along with the barrels, a kit is typically provided that includes a caliber matched probe and magazine. And high-capacity magazines are often available when making these changes, though this is more of an accessory than a component.

The air source is another typical component that includes reservoir tubes or bottles, and often bottles of different sizes and volumes. When building a full-size rifle, a large and high-volume CF tank might make perfect sense. But if the gun is being built as a bullpup, that same tank might be too big or unbalanced. Another key component is the stock, which might be only the pistol grips or buttstock, but could also be an entirely different stock configuration. 

Modular Benefits

We’ve already discussed why your customers might want to build a rifle on a modular platform, to produce a gun that fits their body and style of shooting. Let’s take a closer look at this before moving on to some real-world examples. 

I do a lot of different hunts, but two of my favorites are small game and varmints. When shooting prairie dogs at longer range on the wide-open grasslands, I like a heavier full-size rifle with a long and stable barrel and room to get a bipod well up in front of the forestock. I prefer a large high-magnification scope and a high-volume bottle for increased shot count set up to shoot heavy .25-caliber projectiles. For this application my preference is a tactical stock because I find them easier to shoot from a prone position on a bipod or on shooting sticks.

On the other hand, when in the woods or heavier brush hunting small game, I like a gun that is shorter, more compact and weighs less. I prefer an air tube or small volume bottle, because I don’t need a high shot count or as much real estate on the rails for mounting a large scope or bipod. For this application, I like either a tactical carbine or bullpup configuration because they are more maneuverable and easier to carry over long distances, but I also shoot them better offhand.

Adjustability Advantages

I believe that for a modular platform to reach its full potential, there must be a level of adjustability in the core design. For someone who builds a long-range sniping rifle for prairie dogs and takes all the steps to configure the gun with a new barrel, a new bottle, a new stock, but can’t adjust the performance and type of projectile suited to the application, the benefit is limited.

Most modular designs allow adjustment of the regulator and hammer spring, and some also permit adjustment of the transfer port as well. The bottom line is that these controls allow the user to find the best settings for a specific projectile or set of conditions. So, in the case of a long-range gun, after making all the changes outlined earlier, I might set the hammer spring and transfer port to achieve the highest power output, then adjust the regulator to optimize airflow management while measuring performance over the chronograph. The end point of these adjustments is to achieve the highest power output balanced with the highest level of accuracy and shot count for a given application.

Guns on the Market

There are a few modular airgun designs on the market these days, including models from Air Venturi, Brocock BRK and FX to name some of the leaders in this space. They all offer the attributes mentioned, and I will share info on a couple of the guns I’ve been using extensively.

My choice for an affordable platform is the Air Venturi Avenge-X series. This is a gun that retails for less than half the price of any of the other modular designs and is suited for any level of shooter. I have built two rifles on the Avenge-X Tactical model, one set up for long-range shooting and one set up as my compact squirrel gun. Both are perfect for the intended applications and my style of shooting.

The components used for the long-range gun included the .25-caliber receiver, long barrel (22.8 inches), .25-caliber pellet probe and magazine, 400cc carbon fiber bottle, bottle barrel band and the tactical stock in a Cerakote Sand finish. I set the gun up to generate velocities of 940 fps with JSB Exact King Heavy 33.95-grain pellets, providing .75-inch accuracy at 100 yards for about 70 shots off a 4,351 psi fill. Because I wanted to keep the power high, generate excellent accuracy with a heavy projectile and maintain a high shot count, the large volume bottle made the most sense, even though it weighs more.

The second gun I built on this platform was to serve as a small-game gun used in the woods for closer-range shooting. This carbine version also used the .25-caliber receiver, short barrel (15.75 inches), .25-caliber pellet probe and magazine, 130cc reservoir tube, the tube barrel band and the tactical stock in a Cerakote OD Green finish. 

I set the gun up to generate velocities of 840 fps with JSB Hades 26.54-grain pellets, providing .5-inch accuracy at 50 yards and about 30 shots off of a 4,351 psi charge. Because I wanted to keep mid-level power with the best accuracy, and lightest weight, the short air cylinder made the most sense for this compact rig.

In both cases, I came up with a hunting gun that was optimized for the intended use, and both guns have proven the benefits of the modular concept in my experience. Moreover, both guns are perfect for me. Another hunter might disagree, but they can build their own rifle. That’s the beauty of the modular design.

When it comes to my choice for a premium gun that is modular, I really like the BRK Ghost. Of all the bottle-forward bullpup designs that have gained popularity in recent years, this is probably my favorite. I can’t overstate how good it is in terms of design, ergonomics, build quality and performance. It truly meets the criteria for a “premium” airgun. The flip side is that it is quite expensive, but all the guns in this class are a pretty hefty expenditure for most people. 

This is a case in which switching between components is more practical than building multiple guns from a financial perspective alone. This approach lets customers maximize their investment by using the same core components for different applications; the .177-caliber barrel kit for field target, .25-caliber barrel for benchrest, then mount the .30-caliber and head off on a predator hunt. On the Ghost, the installation of barrel and caliber kit is easy and fast, so it is practical to make the changes as needs dictate.

You can make a solid argument for a modular shooting platform based on application specific optimization, or an economic case for getting the most out of your investment. This is especially true with the more expensive premium guns. But it is the combination of these factors along with  acquiring a gun fitted specifically to individual needs that I find so compelling.