Build an AR-15 Varmint Gun. The AR-15 platform is now considered one of the premium varminting platforms on the market, thanks to the wide availability of parts and components including game-changing upper receiver conversions which allow longer range, flatter shooting cartridges to be paired with the AR platform to take advantage of wind cutting ballistics and dispatch varmint targets over relatively long distances. 

But what does it take to build a practical varmint gun on the AR platform while still not going crazy with the budget? In this article we’ll discuss the different variables involved with selecting components, understanding the varminting landscape, and attempt to help you to narrow down what type of varmint hunting you’d like to do to determine if the AR-15 or the 308 AR platform is a realistic option for you when building your ultimate varmint gun without affecting your bank account too negatively.

The information that follows is meant to be a relatively high level overview of the different variable components of an AR based varminting rifle build, and the general, basic best practices surrounding the idea of building a varmint gun based on tangible and historical concepts which have helped shape the landscape of the varmint hunting industry segment.

Unless you need extreme long range accuracy, an AR can be a nearly perfect varmint platform

The title to this part of the article is somewhat misleading, as the AR can certainly be built for extreme long range accuracy, within reason. For instance, some builds which pay particular attention to detail utilizing specialty cartridges like the 6.5 Creedmoor, for example, are capable of shooting well past 1,000 yards quite accurately. However, when it comes to extreme long range accuracy (meaning 1 MOA or better at more than 1,200 yards), the AR-15 may not be the perfect choice, especially when you can build a simple bolt action rifle that has more capability out-of-the-box than the AR can do at even twice the price point.

All that said, the AR-15 is an excellent format and rifle platform because it offers so much customizability and has so many different component parts available for selection to custom-tailor the experience, as much as the aesthetic, as much as the functionality of the build. 

Overall, the AR-15’s variable build components make it a powerhouse in the varmint hunting world, especially when you don’t need to reach out past, say, six hundred yards or so. And in all reality, for varmints past 600 yards, you’re likely to have a much more interesting and cost-effective hunting trip utilizing a bolt-action and wasting far less ammunition. 

When you talk about reaching beyond 600 yards in any situation, wind and other environmental concerns become such a large deterrent to accuracy that it is often better to try and minimize hiccups by closing the distance on your target.

Because of the very real proliferation of parts availability and custom makers, who just so happen to be geared towards improving the lives of varmint hunters everywhere within the AR-15 space, this platform has become something of a treasure trove for dedicated varmint hunting enthusiasts. And, what better rifle platform to utilize than the AR-15, which can literally become anything you want it to be based on a few key component changes, when you’re talking about a sport like varmint hunting? A sport which encompasses such a wide range of targets, cartridges, calibers and the like. It’s a match made in varmint heaven.

The real benefit to the AR is the modularity when it comes to hunting varmint

Of course it’s obvious to see, and we have commented early on in this article to showcase just how much “X-Factor”, the AR-15’s modularity comes into the game with, when building the ultimate varmint hunting rifle. It is no secret that with a simple upper receiver build change and some optics that have been zeroed properly, just about any user can conceivably change target’s, loads, and accuracy potential within a few minutes, utilizing the AR-15 platform or the 308 AR platform.

More than that, when it comes to defining accuracy on an AR-15, many of the choices you will make are centered around a specific cartridge or a specific core set of component parts. These component parts and cartridges are most affected by the manufacturing process and quality of manufacture of said component parts and cartridges. When mated together, these pairings can have an extreme impact to the positive, on your overall accuracy and ability to hit a varmint target at long range.

And long-range may not be the only range you’ll be taking varmint at. It’s quite conceivable, given the variety of targets in the varmint hunting ecosystem, that you could be aiming at varmint targets from only 25 yd to 50 yd away, rather than having to shoot at targets well past 300 or 400 yards, which used to be the litmus test of a highly accurate varmint option utilizing the native .223/5.56 caliber option of the AR15.

Nowadays, one isn’t locked into the standard configuration of an AR-15 out of the factory. 

An even better example of how to state that concept, is that there is no such thing as a standard configuration of an AR-15 out of the factory, nowadays. 

In fact, the variability of factory offerings is so wide-ranging now that you’d be just as likely to find a .300 Blackout, or a 6.5 Grendel, or even a 6.5 Creedmoor out of factory as you would be able to find a .223 Remington out of factory. This is a good thing for the varmint hunting industry, as more user adoption is available when more options come out of the factory as standardized offerings. In many cases the standardized offerings of today are perfectly mated to a specific target in the varmint world. 

Another big benefit is the popularity of the AR enhances the depth of loads available for varmints

Clearly the popularity of the AR-15 and the 308 AR platform have been a direct result of the availability to different cartridges, calibers and loads as well as the different envelopes the AR platform can push in order to help drive revenues for new startups in the field, and the old players who’ve been here all along. 

Where there is demand, the AR marketplace will adapt and provide supply. And in the case of the varmint hunting Juggernaut, there have been whole segments of the market brought to life by the idea of stalking tiny, annoying animals we like to call varmint.

From specialty one-off barrel makers, to those providing full factory kit, direct to you as a fully functional rifle dedicated to dispatching Little Critters in a prairie somewhere, the AR marketplace has become a veritable smorgasbord of offerings that can be finely attuned to whatever you desire as a hunter or sport shooter. In the case of varmint hunting, there are plenty of options that rely upon the plethora of loads available to a varmint hunter. This is especially true when you are talking about The newer, screaming fast, low grain weight loads that offer a nice balance between long distance targeting and low cost per round economics.

One of particular interest to the varmint Hunter is the .224 Valkyrie. Which when you look at it from a surface level perspective offers everything that most varmint hunters are looking for in a cartridge. The abundance of loads available for the .224 Valkyrie, ensured that it was one of the industry Innovations Of The Year a few years back. And you won’t hear anything in this article to trivialize that accolade. From a varmint hunters perspective the .224 Valkyrie ticks a lot of boxes on the checklist. 

Alas, it is not the only cartridge that makes sense for varmint hunters. And some of those cartridges do not lie squarely in this part of the spectrum only made up of lightweight projectiles that go out of the barrel at near-hypersonic velocities.

The ballistic improvements of the last decade or so are showing up where it counts for the AR platform

Another particularly interesting cartridge to the discussion here is the 6.5 Creedmoor, and the 6 mm, which both could be used to dispatch coyotes. And while coyotes may not be squarely within the realm of ”varmint hunting”, one could make the case that coyotes are certainly within the spectrum of the varmint hunting concept. And the 6.5 Creedmoor and the 6 mm both offer the type of ballistic advantage that makes a lot of sense for the skittish coyote that likes to hover well past 300 yards from the shooter. It also offers the same type of velocity that makes coyote hunting so enjoyable. 

Note: there is a lot of buzz around loads like the 6mm AR right now, but we have chosen not to highlight it in this article for various reasons – mostly lack of proven prowess and mainstream widespread parts availability.

And, while on the topic of coyote hunting, one might consider at least in some carryover aspect, that the idea of varmint hunting definitely has the ability to form a Venn diagram with the idea of depredation, including feral hog hunting and moderate-to-large cat hunting, including fox and bobcat. Of course, your mileage may vary, based on state regulations, hunting traditions and geographic location, but the carryover exists nonetheless. 

Simply put, one might feel quite confident utilizing the .223 Remington or a 5.56×45 mm in pursuit of moderate cats, feral hogs and other predators like coyotes. In fact, probably a larger percentage of these types of activities are perpetrated with standard AR-15s utilizing those cartridges rather than some of the specialty cartridges mentioned above. Nevertheless, ballistic improvements over the past decade or so, have contributed greatly to the abundance of new user adoption within the depredation and varmint hunting ecosystems.

One might also consider some of the other rounds currently available that offer unique specific capabilities within these two areas that are so popular, currently. And it is this author’s opinion that it’s very difficult to decouple the idea of depredation when talking about varmint hunting. One could argue that the idea of varmint is more about the nuisance factor, then it is about a specific type or genus of animal. And in the case of coyotes, feral hogs and moderate and large cats, that argument is certainly one that has some legs.

The .300 Blackout is a perfect stealth option, though it may be a mainstay on the anemic trajectory spectrum for normal varmint hunting needs, and might be a bit large in the projectile grain weight spectrum for most mainstream varmint hunters. It should go without saying, however, that the ability to use a suppressor and a subsonic round when a hunter can use a varmint hunting rifle in a range of under 200 yards, that the .300 Blackout might be an excellent option.

The 6.5 Grendel, as well as the 6.8 SPC, and the 300 Ham’r, and even the 350 Legend are all obvious options depending on the specific target at hand as well. When you’re talking about a range of under 550 yards, where a larger grain weight might make sense, these are all excellent choices. 

This is especially true if your varmint hunting borders more on the depredation side of the spectrum then on the cute, furry, varminting side of the spectrum. While an all out exploration of some of these larger  grain weight options might make sense when talking strictly about depredation, for the sake of this article we won’t dive too deeply into their capabilities or specific ballistic advantages, except to say that they are certainly options depending on the type of target you’re after while varmint hunting. All of these fit into the AR platform easily, and have a robust market ecosystem to support their individual endeavors.

Finding the right mix of components is the biggest challenge in building an AR-15 Varmint Gun

Generally speaking, when referring to the varmint hunter’s best practices, or Varmint Hunting 101, the faster, flatter, and lighter the projectile, the better. This is true for a lot of reasons. Mostly, the benefit of being able to watch as you pull the trigger and feeling the lower recoil barely affect your view of the target while a screaming fast projectile hits it, is the focal point.

It’s also not particularly sportsmanlike to completely obliterate a target when it is unnecessary. Most small critters are easily dispatched with premium loads that feature faster, flatter shooting, lighter projectiles, and this allows the shooter to feel good about matching the cartridge or caliber or even the load to the target. Furthermore, in flat conditions, these types of rounds typically offer excellent accuracy. 

And that’s the point of most rifle builds in the varminting spectrum: accuracy.

When it comes to providing accuracy and delivering a payload on target exactly where you expected it to land, there are a few key components to pay attention to from the AR-15s perspective.

AR-15 Barrels for varmint hunting

The barrel is perhaps the most important part. But perhaps not quite as you envisioned it. It matters less, the price point and the bespoke nature or the individual barrel manufacturing process. What matters more is mating the particular length of barrel, chambering style, and rifle twist rate to the actual load you plan to shoot out of your rifle. 

Other than the ammunition, and the optic, and the environmental factors, This particular pairing will have more impact potential on your accuracy and ultimately on your success at longer ranges in varminting than any other single component part.  That is to say: one is always trying to optimize the trajectory, stabilization, and point of aim – to the point of impact from the bore exit to the target. 

And, in the case of a hardware consideration, other than an optic that is properly dialed in, and properly mated to the environment, range and target type, the barrel twist rate and an optimized barrel length made specifically for the load you intend to shoot through the gun, will have considerable impact on your overall accuracy.

Stability of your shot during the varmint hunt

Generally speaking, varmint hunting takes place in a relatively controlled environment; this is particularly true when you’re talking about longer-range varmint hunting activities. The farther away you are from your target, the more comfortable and relaxed you will be, and the larger the set of infrastructure you can put into play.  Therefore it should go without saying that balance and stability which contributes directly to shot consistency and accuracy will be paramount. 

Specifically, one might consider the overall balance of the rifle, and where the gun rests while sighting in on target. This may be on a bipod, tripod or even in a prone position or from a table dedicated to improving accuracy. Where you CAN introduce stability and shot consistency, you SHOULD do so. Even if it means utilizing a sling to increase tension and improve balance with your rifle, if it’s your only option. Otherwise, a rock-solid bipod or tripod makes a lot of sense. This is also true for general depredation.

The right varmint hunting trigger for the AR-15

The trigger componentry is also a special consideration when talking about varmint hunting. After all, shot consistency, and shooter peace of mind and ease of implementation, will improve overall accuracy. With the right trigger group, one can expect drastic improvements in overall accuracy, or at least in shot consistency. When you have better shot consistency, inherently you will have better accuracy.

Other components and considerations for the AR-15 while varminting

Other considerations a varmint hunter might make when it comes to the overall component selection includes the following in no particular order:

  • Barrel shroud/forend mated to the upper receiver with a rock-solid barrel nut
  • Tolerance-matched upper and lower receivers
  • Lapped upper receiver and hand-tuned carrier and bolt components
  • Exceptional Optics (note: optics can have perhaps the largest impact on your overall success as a varmint hunter when it comes to accuracy, and is simply listed in this component list as a reminder –  it is expected that most varmint hunters will be using sophisticated optics at intermediate and long ranges)
  • Adjustable buttstock or other ways to balance, or otherwise manipulate overall consistency to your advantage

What types of varmint are in the AR’s sweet spot

It’s hard to quantify what types of varmint are in the AR “Sweet Spot” considering the huge amount of caliber and cartridge options that are available to the AR. That includes both the AR-15 and the AR-10/308 AR platform.

For the purposes of this discussion will include depredation as part of the varmint hunting equation, but your mileage may vary here as well, as you may have real-world experience that exceeds the basic structure of the following cartridge/varmint pairings.

How far, how fast, how accurate? What are the parameters of the AR as an ideal varmint focused platform?

For comparative purposes, we have used a single manufacturer of ammunition to help visualize the breadth of the market available options. In this specific case, we have chosen Hornady (Wilson Combat in a single case as well), but other manufacturers’ lineups would likely be substantially similar. This was an arbitrary choice, and the article is not championing one brand over another – it is simply for comparative needs.


For the AR-15, it goes without saying that the .223 Remington and the 5.56x45mm are excellent rounds up to about 350 yd, in flat or generally mild conditions when targeting varmints in the range of 3 lbs. up to about 125 lbs. This includes smaller feral hogs as well as moderate and larger cats, and coyotes. The only caveat when it comes to the native rounds for the AR-15 platform, is that there might be an awkward pairing here or there, depending on environmental conditions which may upset your ability to dispatch a target cleanly at extreme ends of the spectrum. 

Generally speaking, anything within that weight class and that range spectrum will be achievable in the varmint hunting world given these two cartridges. These cartridges are also quite economical to shoot, and there is a massive amount of loads available for the varmint hunting realm with regards to these specific calibers.

You can find a large amount of options in any manufacturer’s lineup from an ammunition perspective. For instance, you might utilize a 35 grain projectile, which is suitable for varmint up to 50 lb, and likely to be usable out past 300 yards, however with some substantial drop at that point. This lightweight projectile moves out of the barrel at 4000 feet per second velocity with 1243 foot pounds of energy at the bore exit. At 400 yd there is a 17.3 in drop. At three hundred yards there is only a 5.3 inch drop.

Comparatively, from the same manufacturer: in a 55 grain projectile weight you’re likely to see velocities of 3240 feet per second velocity out of the muzzle with 1282 foot-pounds of energy. At three hundred yards you would see approximately 7 inches of drop and at 400 yards you’d see 21.4 inches of drop. At 400 yd velocity would be above 1850 feet per second with energy around 425 foot pounds.

Pushing into a 68 grain boat tail hollow point from the same manufacturer you would expect to see 2960  feet per second velocity at the muzzle with 1323 foot-pounds of energy; at three hundred yards there would be a 7.5 inch drop and at 400 yards you’d see a drop of 22 in. At 400 yards you would still see 1993 feet per second velocity and approximately 600 foot-pounds of energy.

All three of these example rounds would be suitable for varmint anywhere in the range between 3 lbs and 125 lbs, or even greater than that, depending on the situation, and the environmental conditions. 

.224 Valkyrie

When you need to reach out past about 550 yards, or need and exceptionally fast round that can be pushed out of the AR-15 platform natively, the 224 Valkyrie probably makes a lot of sense on varmint targets anywhere from 15 lb up to about 125 lb and at a range of up to about 650 yards. This will be an excellent round for coyotes, or even for smaller targets like prairie dogs or groundhogs, given the extreme range or need for the more potent ballistics over that reach.

Comparatively, with the .224 Valkyrie, relative to its nearest competitor in the 223 Remington, for example you wouldn’t see as much deviation in velocity or energy at the target over longer distances, and you would see a slightly flatter drop curve even though do you have a larger amount of drop thanks to the substantially heavier grain weight. For example, with an 88 grain projectile you’re likely to see 2675 ft per second velocity out of the muzzle and 1398 foot-pounds of energy;  at 400 yards you’d maintain 2060 feet per second velocity and more than 820 foot-pounds of energy with a drop of about 23.7 inches. 

Given the extra 20 grains of weight you can see that these compete pretty favorably, and actually make more sense in favor of the .224 Valkyrie over the .223, even though, for the money you might be able to make a case for the 223 on most targets. Where that extra grain weight might make sense is when you need to dispatch a larger target above the 125-pound range at extreme distances within the overall range capabilities of the cartridge.

6.5 Grendel/6.8 SPC/.300 Ham’r, et al 

While it’s not fair to lump together these three rounds and those other cartridges that fall basically in line with the general ballistic spectrums for these types of loads, because each of them has their own redeeming qualities, it makes sense when you’re talking about what the sweet spots are for the given cartridge options on the AR-15 platform. 

In the case of these 3+ cartridges, they mostly make sense when you need a higher grain weight on target, and where your range will not exceed 400 yards, but where you need more ballistic advantage to ensure a clean kill. This is particularly true when targeting predators, rather than cute and cuddly traditional targets for the varmint hunter.

You’re likely to see some benefit if you need to have a more compact rifle, when using the 300 Ham’r. Out of a 16.25 inch barrel using Wilson Combat loads (because they are currently the only mainstream manufacturer of the cartridge), you would likely see a 110 grain Sierra hollow point with 2600 ft per second muzzle velocity and 1650 foot-pounds of muzzle energy. Comparatively, a 150 grain Hornady SST projectile would be 2290 ft per second muzzle velocity and 1747 foot-pounds of muzzle energy. But remember, this is coming out of a 16 and a quarter inch barrel and has long-range capabilities at least in the same vein of the 5.56 or the .223.

When comparing the 6.8 SPC to the 6.5 Grendel you’re likely to see some basic concepts play out, including that the 6.8 SPC is going to shoot slightly flatter while the 6.5 Grendel is going to deliver more energy and velocity On target at range. That said both are substantially similar and play in a grain weight range that allows you to hunt smaller varmint and even bridge into larger game. Both are excellent options for depredation; especially at the 200 to 400 yd range.

With a 110 grain V-Max bullet out of the 6.8 SPC you would see 2550 feet per second velocity out of the muzzle and 1588 foot-pounds of energy. At three hundred yards there would be an approximate 10.4 inch drop and at 400 yards a 30.6 inch drop while maintaining a velocity of 1700 feet per second and an energy of 706 ft. lbs..

In the 6.5 Grendel and a slightly larger grain weight in a full metal jacket with 123 grain projectile, you’re likely to see 2580 feet per second velocity at the muzzle and 1818 foot-pounds of energy. At three hundred yards you’d see a 16.7 inch drop and at 400 yards there would be a 37.6 inch drop but you would maintain a higher velocity and higher energy at the target. For example at 400 yards you’d see approximately 1815 feet per second velocity with 900 foot-pounds of energy delivered at the target.

Using the AR-10 or other .308 based AR platforms as a varminting platform

Perhaps you’ve seen the writing on the wall at this point, whereby the .308 AR platform makes a lot of sense for long-range varmint shooting; especially when you can utilize the 6.5 Creedmoor and there is some carryover between other activities you might be using this rifle platform for. 

Now to be clear, it’s not exactly evident in most people’s minds that the 6.5 Creedmoor is firmly established as a varmint specific round. However, because it is fast, flat, and accurate it will make sense in many scenarios. And let’s be clear: it is certainly not varmint specific as it is made more for the target and competition aspects as well as bridging into larger game over longer distances.

6.5 Creedmoor

And it should go without saying as well, that you might not need to explore too many other options in the .308 pattern AR, other than the 6.5 Creedmoor, because it does so well at the fast, flat, accurate game.

With a 90 grain V-Max Varmint Express projectile, the 6.5 Creedmoor is going to exit the muzzle with 3300 feet per second velocity and 2297 foot-pounds of energy. At three hundred yards there would be an approximate 5.7 inch drop; at 400 yards there’s an approximate 16.9 inch drop and at 500 yards there’s an approximate 34.8 inch drop. At five hundred yards you’ll still maintain 2068 feet per second velocity and 900 foot-pounds of energy.

Moving up in weight class with a 140 grain boat tail hollow point in the American Gunner line, the 6.5 Creedmoor is going to exhibit 2690 feet per second velocity at the muzzle with 2249 foot-pounds of energy. At 300 yards there’s an approximate 8.1 inch drop; at 400 yards there is an approximate 23 inch drop and at 500 yards, there’s an approximate 45.8 inch drop, but at five hundred yards you maintain 1972 feet per second velocity, and 1209 foot-pounds of energy. 

Some conclusions about building an AR Varmint gun

Generally speaking, most shooters who have an idea about varmint hunting with an AR-15 or an AR-10 platform, generally see varmints classified as animals like gophers, groundhogs, muskrats, prairie dogs, rats, squirrels, Etc. But, when you broaden the concept to include invasive species as well as predators, like bobcat, cougar, coyote, wild dogs, foxes, raccoons, weasels, wolves, and even Birds, or other invasive species like hogs, and javelina, the spectrum broadens as to which types of cartridges and what types of AR builds you’d be prioritizing to make a spectacular varmint rig.

Of course, it’s important to understand that some of the regulations for your specific locale, including state and local hunting definitions, will dictate some of what you can or cannot do when hunting any of the animals listed above. In fact, in some locations and jurisdictions some of those animals aren’t considered varmint, or have very strict controls over how they can be hunted.  Some areas even prohibit hunting with a rifle and prefer varmint focused efforts be geared towards trapping instead of hunting. Because of this you will need to determine what is legally allowed in your area and how to proceed from there. The scope of that topic is far too broad to even give a high-level overview in an article like this.

The purpose of this article wasn’t to try and redefine what you believe a varmint is, but instead to give a high-level overview of what’s possible with the AR-15 and the pathway you might travel down in determining how to build that rifle, optimized for your specific brand of varmint hunting. 

To give a broad-based conclusion, after all this discussion, what it really comes down to, is which parts will you prioritize to ensure that you have the type of accuracy that you want to make the hunt a fun event for you and your fellow shooters, while determining which caliber cartridge you’d like to be married to at least for the foreseeable future. 

The idea of fast, flat and accurate is a good rule of thumb, and any of these cartridges are capable of taking any varmint from the miniscule prairie dog, up into wolf, and hog, and javelina-sized animals. Certainly many of the listed cartridges or load concepts would be overkill for many of these targets, and that’s okay in many scenarios, but you will have to determine what makes sense for you.

In the end, there is always the humble add-on, drop in AR-15 conversion kit that can help you change on-the-fly, what you need to accomplish your goals. 

For most varmint hunters though, they already know what problem they’re trying to tackle, and building a tool to help them accomplish that goal is precisely what we wrote this article for. In the case of the hunter whose ranch is overrun with rodents, they might be perfectly fine with a 22 long rifle, even on an AR-15. 

But for those who have multiple issues plaguing their property or who have a specific target in mind, they should definitely look to build towards the target or towards a desired, functional, core-concept, the best of which, we feel, is building around an interesting cartridge.

The AR-15 (and by extension the 308 AR) gives you the choice, and the plethora of loads available on the market allows you to pretty much fit any square peg into a round hole or vice versa, as the need arises in your neck of the woods. This is why we believe the AR makes for the most practical and most interesting platform for varmint hunting.