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How to build the best AR for Hunting

[h2]Can you build a top notch AR for hunting with a simple Upper Receiver Swap?

This article is about building the best AR for hunting and considering how easy to work on and affordable lower receivers are, plus the wide variety of components and build styles that exist in the AR market, there are plenty of options. The obvious first question is – can you build the RIGHT AR with a simple AR upper receiver swap? The quick answer is for some people – yes you can. Especially if you hunt a single game type and use it generally for hunting purposes, and don’t need cross-discipline capability. 

The longer, more accurate answer is that it’s not usually just as simple as committing to a cartridge or a dedicated upper, if you need to use the AR you’re building for more than one thing, or if you want to hunt a wider range of game. 

Let’s address the elephant in the room early on, though: The AR is a versatile hunting option for just about any game option up to 450lbs in common market-plentiful options. For many, the standard market offering for the AR rifle is going to cover a wide range of game for their annual hunting needs.  

The above information in the simplest form is this: A standard 5.56/.223 AR with a mainstream build is going to get you from prairie dogs to big deer pretty easily – though, you’ll need to rely on specialty rounds to do it most effectively. 

The rest of the variables address the nuanced part of the equation, The likely reason for which you are still reading.

Let’s deep dive into the nuances and concepts behind building a great AR for hunting the way that you want to hunt. 

[h2]Building the perfect AR rifle for hunting comes down to what you want to accomplish

You can pick a cartridge because the ballistics seem impressive and build around it, which will give you a great focal point. But it may not help you build around a core principle or a variable set of ideas you want to accomplish. We cover that very concept later in the article, if you like the idea of building around a caliber/cartridge. 

For now, instead, it seems to be a much more effective way to build a truly great AR for hunting, by addressing core principles, not just settling on a cartridge. 

[h2]While it can be good to build around a cartridge – the best way to pick the right AR is to focus on where and what you are hunting

What does the environment look like? There are 15+ different cartridges with significant support on the market that work on the AR platform and offer a competitive option against the 5.56/.223, so defining a core set of needs may help you decide on a way to address your build in that fashion. 

For brush-dense areas you’ll want a heavier projectile that can maintain accuracy over a shorter range, but hit harder after a potential hit on debris or passing through forest or brush. 

Similarly, where you have peaks and valleys, you will want to adapt your build to accommodate a cartridge that can utilize a flight-stabilized, tack driving round with a flatter trajectory. Updrafts can push a light projectile around, and you will need to deliver terminal ballistics on a down range target at the edges of some cartridges effective ranges. For some, this means that the normally capable 5.56/.223 won’t be “enough gun” for the target or the environment. 

In areas where there are significant side winds, you will need to find the balance between enough projectile weight, and enough velocity to cut through the destabilizing effects of those windage altering drafts. 

For wide open spaces you may be fine with a smaller projectile, but will you be comfortable with the stopping power? What environmental variables will affect your shots. You often won’t get a second shot opportunity, even if you’re very experienced in a situation where you are shooting in under 250 yards because you’ll spook animals, etc. Your scent or your physical presence may become a problem in those types of ranges too, so a single shot stoppage is a big part of the plan.  

Are your optics dialed in for the load? Say you’re going ultra-stealthy with a suppressed .300BLK, in an area where you are stalking a big game close-in (ideally). Have you compensated for bullet drop, or can you do so on the fly when you need to take a target at 275 yards instead of 135 yards? These types of considerations are necessary to ensure a good outcome on every hunt. Planning is a big equalizer – especially when you have your own big ideas on optimization but Mother Nature or the environment say otherwise. 

Hunting is like that: Hunters want to do what they like, with their own style, and the weather, the animals and the terrain always have different ideas. Maybe you couldn’t care less to spend money on a tax stamp to get a suppressor for a deer hunt. The fact remains: no matter how you choose to hunt, you’ll need to be aware of the nuance of environmental factors.

[h3]What game are you going after? How to build the best AR for hunting based on the game you hunt

Prairie dogs and squirrels can be taken with ultra light projectiles. But those same projectiles might not be ideal for bigger game, and while you can reasonably straddle that range with a 5.56/.223 Remington, it’s not ideal, even with a forgiving barrel twist rate. Nevertheless, if you want to, you can do it, as long as you keep your expectations within the basis of reality. You’re going to lose range on bullets that aren’t properly stabilized, so where you thought you might get out to 400 yards with the range of projectile weights your barrel can handle, you might need to factor as much as a 35% difference into your calculations depending on those targets and distances. 

Some key points to consider:

  • Bullet weights and bore twist rates are an important factor – know your extremes, and make sure you are utilizing great loads to take advantage of ballistic optimization
  • Planning for “more gun” than you thought you would initially need may be a good remedy if you desire a bigger range of game targets, especially when you can objectively identify potential cartridges by separating them into groupings by weight or by range. 
  • Upper receiver builds can help to broaden your range of target weights, projectile effective ranges and terminal ballistic performance – but it can get costly quickly, and you’ll need to plan well
  • Optics need to be dialed in properly and changing optics mid-hunt can be very difficult – choosing a monolithic mounting option that is easier to dial in on the fly, and knowing your optics well will be helpful
  • Knowing your game targets and environment, or relying on the experience of guides or other hunters from the area for information is a best practice – especially before you optimize loads for your specific hunting trip
  • Not trying to ride the line of the extremes for your chosen rifle solution will lead to far fewer headaches
  • Sometimes, it’s worth investing in a gun that’s specifically built for a certain game type and environment if it can mitigate concerns or help to guarantee success

[h3]Where will you be hunting with your AR? How to pick the best AR for hunting based on location and environment

Remember that concept of environmental factors showcased earlier? That is a huge variable and can help you to identify problems before you take a shot and miss in the field. 

The biggest environmental impacts will be calculated from (not necessarily in order):

  • Distance of a typical target for the hunting area
  • General animal behavior for that area/season
  • Pre-trip preparations
  • Wind impacts from up or down drafts (caused by terrain and elevation changes over the distance), or from side to side or cross wind travel, caused by terrain layout in relation to the specific shot taken
  • Load and rifle build optimizations in relation to the impacts listed above
  • Debris along the shot trajectory; including heavily wooded, or densely impacted areas in brush

Distance/range issues are best mitigated by choosing a long-range optimized caliber and picking a well-matched barrel twist to the load you are brigning.

General Animal behavior is best equalized by good pre-trip intel, and bringing “more gun”. 

Pre-trip preparations like proper understanding of the topography and basic wind patterns can help to ensure smooth transitions, and permit you a lot more flexibility when taking longer-range game targets.

Skewing towards heavier projectiles with more mass (and the proper powder behind them) can help to cut the wind issues (within reason). Going up a class in cartridges can also help in this case. At the very least, having a more capable, longer-range round will give you margin for error. Opting for high velocity loads that also adequately allow for a heavier projectile can help mitigate some wind impact as well – though in some cartridges/calibers this combination may not be possible. 

Make sure that you are load optimizing at least for twist rate in regards to projectile size and length, and that you are utilizing hunting specific rounds. If you need to add grain weight, using an all-lead bullet can help – but check jurisdictional regulations to ensure lead is still an allowable option. Using handloads that push the boundaries can also help, but make sure not to use overpressure rounds or rounds that are otherwise loaded to an unproven or unsafe level. 

Taking reasonable shots when given unexpected environmental challenges is all the more important. 

[h2]Some basics on Ballistics/Performance by groups of behavior for the Cartridges

Hunting obviously necessitates contemplating caliber and cartridge when determining how to choose a firearm.

[h3]Great longer range cartridges

On the native AR-15 platform, the following Mainstream cartridges provide excellent ballistics for longer range shots on big game:

  • 6.5 Grendel
  • .224 Valkyrie
  • .300 Ham’r

Relative to each other (because they occupy a tight range of ballistics) the three cartridges are each sorted according to their specific optimization effects in relation to only the same class of cartridges. 

The 6.5 Grendel has the best long range energy and adequate velocity at the target, but may not be as fast as the .224 Valkyrie and may not have the same shorter range stopping power of the larger diameter .300 Ham’r. 

The .224 Valkyrie has excellent speed and good accuracy, as well as a favorable trajectory over longer distances, but may not have the overall power on target at extreme distances nor the diameter and mass of the other projectiles – depending on load. Generally it is a fast and flat round, with slightly diminished overall ballistic potential at longer distances and it is possibly less performant in higher wind scenarios. 

The .300 Ham’r is a less proven round by overall exposure and timeline, and is meant to compete favorably in shorter range scenarios on a wider range of game to include heavier weight targets. Furthermore, it is heavier and includes more mass on target, and while it may have comparisons in accuracy, the additional heft will contribute to a larger drop ratio over

extreme ranges. That said, it seems the clear winner in short or intermediate distances when compared to the other two cartridges in the space, despite being suitable for longer range situations, too. 

Each one listed above has fantastic value over longer distances than most hunters would consider an AR to be viable, and represent a clear win for the AR market, and hunters who embrace the Black Rifle for hunting of larger game at longer distances.

On the larger AR platform (.308 pattern), the following mainstream Cartridges provide excellent ballistics for longer range shots on big game:

  • .308 Winchester
  • 6.5 Creedmoor

These calibers are covered more in depth, lower down in this article. 

[h3]Great shorter range cartridges

The shorter, stubby type AR rounds are a compelling option for brush gun usage and offer a huge ballistic advantage where the engagement will not exceed 200 yards; and particularly where the engagement of a target will take place in heavy or dense brush or forest and is under 75-100 yards. 

Several rounds here make sense, including .350 Legend; .458 SOCOM; .450 Bushmaster and the .50 Beowulf, among others. 

The ballistic numbers don’t need to be stated given the obvious bias towards energy delivery and the absolute understanding of the heavier mass projectiles and the sloping trajectories that come along with the more admirable characteristics. The comparisons may be more confusing than a help to prove the argument given the large difference in focal points. Needless to say, these cartridges are meant for massive energy dump and huge wound channels, instead of other historically more enviable terminal ballistics. 

[h4].223 Remington/5.56x45mm

A safety note: These cartridges are substantially similar but they are NOT identical. The crossover use should be investigated prior to shooting. The .223 Remington is loaded to a lesser pressure maximum, and generally if a barrel is not marked as capable of a 5.56x45mm NATO, you should not shoot the higher pressure round (5.56) in it. .223 is generally safe to shoot in a barrel marked “.223 Remington”, or “5.56” or “.223 Wylde”. A 5.56 is generally safe to shoot in a barrel marked “5.56” or “.223 Wylde” BUT NOT in a “.223 Remington” Barrel. 

The organic loadout for the AR platform is a very good cartridge option for when you need to take a wide range of animals in a given weight range, as it can handle smaller game like coyote (or even smaller), can be used effectively on hogs, deer and just about anything else in most conditions within the 275-350 yard range and up to 350-400 lbs pretty reliably. Some careful

optimization and load curation can increase those numbers by 25% too, if you match components and loads properly. 

All that said, the cartridge, even in its most optimized format, with its most optimized load, provides a good general use case, but doesn’t necessarily outperform any of the other mainstream cartridges on any specific game type or at any specific range. 

[h4].300 BLK 

An interesting factor for deer sized game targets when it comes to the .300BLK is that you can bring your suppressor (check your jurisdictional/state laws prior to making that decision) and bring loads for subsonic AND supersonic use. This allows you to take advantage of the shorter distance, slower, quieter loads if you can, and if needed, you also have access to a round that behaves more like a .308 (minus some terminal ballistics, trajectory and range).

This is why this is such a popular round for those who want to build a single gun that can do more than just take big game. Such a configuration is great for home defense, range use and general sporting needs. Of course, adding a suppressor requires a comprehensive background check and a tax stamp. It may not be able to be justified by all hunters for one or more reasons. 

h4].308 Winchester/7.62x51mm

A safety note: These cartridges are substantially similar but they are NOT identical. The crossover use should be investigated prior to shooting. The 7.62x51mm is loaded to a lesser pressure maximum, and generally if a barrel is not marked as capable of a .308 Winchester, you should not shoot the higher pressure round (.308) in it. A .308 is ONLY safe to shoot in a barrel marked for that specific cartridge. Generally, a 7.62x51mm can be safely fired from a barrel of either a “.308 Winchester” or “7.62×51”.

One of the most versatile rounds for big game that can be put onto an AR platform is the .308/7.62x51mm. The variety of loads from the 55 grain “sabot” projectiles to the 200+ grain weights allow you to take all types of game reliably to 650 yards generally. 

It requires, however, that you are utilizing the larger .308 pattern AR platform. This round and the 6.5 Creedmoor below will not fit on a standard AR lower receiver.  

[h3]6.5 Creedmoor

When you need to take long shots and need at least adequate ballistics for larger game targets. 6.5 Creedmoor has enough ballistic impact on target that you can compensate for the smaller diameter and the lower overall grain weights compared to larger calibers. But the cartridge shines in ranges above 650 yards where wind is a problem early on, or where you need to know you will be on target at the target’s range. 

It’s preferable to other rounds in ultra-long range situations because, even though it needs the larger .308 AR platform to run the cartridge, it is “more than enough gun” for about 70%+ of all the big game in North America and is generally distance-agnostic relative to any other AR platform cartridge options. 

Conclusions about how to build the best AR for Hunting

Yes of course caliber matters. But it’s arguably not the most important factor for the choice of components or a starting point. It makes sense, instead, to build towards a goal and a known focus, like the type of terrain you are likely to hunt going forward and the type of game you intend to hunt for most often. ALL the listed cartridges could be a good fit for intermediate game out to short and intermediate ranges; many are suited for larger game and longer distances. But what matters more than anything, is that you would be comfortable shooting it, and knowing that you shot will land where you expect it to. Further – without ballistic numbers – would your shot effectively take down your target. 

One cannot rely solely on the experience of others and some lab results to determine the effectiveness of a system used to mitigate inconsistency in a practice that is made from a series of inconsistent behaviors, like hunting. 

In the end, because of the proliferation of parts and the modularity of the platform and its longstanding relationship with hunters and sportshooters everywhere, the AR will be around even if you make a decision to support a given cartridge and find out later you want something different. What is likely to be in effect for a long time, is where and what you hunt; and the ever-present threat that ballistics will get better and engineering will get better and technology will get better. That’s a “threat” that hunter’s everywhere should be happy about. Optimize for your known parameters and let the rest fall into place – that’s our take on building the best AR for hunting. 

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Source: Huntinglife