May, 21

Upgrade Your AR-15: The Ultimate Guide to 40 Cal Conversion

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Looking for a way to upgrade your AR-15 rifle without breaking the bank? Look no further than the 40 cal AR-15 conversion kit! With this simple addition, you can transform your standard firearm into a high-powered machine capable of taking on any challenge.

The 40 cal AR-15 conversion kit is designed to provide shooters with improved accuracy, range, and power. Whether you're looking to take down big game in the wild or hit targets at extreme distances on the range, this innovative piece of technology has got you covered. And best of all? It won't cost you an arm and a leg like other performance-enhancing upgrades.

So if you're ready to take your shooting experience to new heights with the 40 cal AR-15 conversion kit, read on. In this article, we'll break down everything you need to know about this exciting innovation in firearms technology. From its benefits and drawbacks to installation tips and tricks – we've got all the information you need right here!

40 Cal AR-15 Conversion: Everything You Need to Know

If you are a gun enthusiast, then the idea of converting your AR-15 to shoot .40 caliber ammunition may have crossed your mind. And why not? The .40 cal is a popular choice among handgun owners, offering better stopping power and accuracy than the 9mm. But before you start shopping for conversion kits, there are some things that you need to know.

What is an AR-15?

The AR in "AR-15" stands for Armalite Rifle – the company that designed it in the 1950s. The rifle itself is semi-automatic and fires one round per trigger pull. It was initially created as a civilian firearm but has since been adopted by various military units around the world.

Why Convert Your AR-15?

There are several reasons why someone might want to convert their AR-15 chambered in .223/5.56 NATO cartridge into one capable of shooting .40 S&W rounds:

  1. Increased Power – The larger diameter bullet provides more stopping power than its smaller counterparts.
  2. Accuracy – Due to its larger size, it's easier for shooters using iron sights or optics like scopes or red dot sights.
  3. Versatility – If you already own both an AR and pistol chambered in .40 S&W (or plan on purchasing them), having two weapons with interchangeable magazines can be very convenient.
  4. Cost Savings– Switching uppers instead of buying another complete weapon can save money over time.

How Does One Convert an AR-15 To Shoot .40S&W Rounds?

To convert your rifle from firing standard rounds (.223 Remington/5.56x45mm NATO cartridges), there are two options: buy a dedicated upper receiver intended only for this purpose or purchase a conversion kit made specifically for this purpose.

1. Dedicated Upper Receiver

This option involves buying an entirely new upper receiver assembly that is designed specifically for shooting .40 S&W rounds. The process of swapping out the upper receiver is relatively easy, requiring only a few simple steps:

  1. Disassemble your rifle and remove the existing upper assembly.
  2. Attach the new .40 S&W dedicated upper to your AR-15's lower receiver.
  3. Reassemble the rifle.

One thing you should note is that while this method can be an effective way to convert your rifle, it does require additional time and money investment.

2. Conversion Kits

The second option involves purchasing a conversion kit which allows you to modify your standard AR-15 chambered in .223/5.56 NATO into one capable of shooting .40 S&W rounds by replacing some parts like bolt carrier group, barrel, and magazine adapter.

Comparing Dedicated Upper vs Conversion Kit: Which Is Better?

When choosing between these two methods for converting your AR-15 there are pros and cons to each approach:

  • Cost: Buying a dedicated upper will generally cost more than buying just a conversion kit because you are buying an entire new unit built from scratch instead of modifying existing components.
  • Ease Of Installation: A dedicated unit requires only disassembly/reassembly while installing conversion kits may need some gunsmithing experience as well as specific tools
  • Accuracy: Dedicated units offer better accuracy than conversions since they were specifically designed with one caliber in mind but if done right conversions don't have much impact on accuracy either
  • Magazine compatibility: When using converted magazines – are often less reliable or more prone to malfunctions compared with original magazines which can be used with both options

Ultimately deciding between these two methods comes down mostly personal preference based on budget constraints or how confident someone feels working on their own firearm versus paying professionals for installation assistance/modification services

Tips for Converting Your AR-15

If you decided to go with the conversion kit option, here are some tips that can help make the process smoother:

  • Choose a quality conversion kit: Make sure to choose a reputable manufacturer and model of conversion kits. Low-quality kits can cause malfunctions or even damage your rifle.
  • Clean your rifle before and after installation: This will ensure proper functioning of all the parts involved in converting it.
  • Follow instructions carefully: Whether installing yourself or having someone else do it, following instructions is critical for safety and optimum performance.


Converting your AR-15 into shooting .40 S&W rounds is entirely possible, but it's important to choose which method works best for you based on budget constraints/time investment vs personal comfort level working on firearms. If done right this modification will give you increased stopping power accuracy versatility as well as cost savings over time.


What is a 40 cal AR-15 conversion kit?

A 40 cal AR-15 conversion kit allows you to convert your standard .223 or 5.56mm AR-15 rifle into a more powerful handgun caliber. The kits usually include a new barrel, magazine, and bolt carrier group. It's important to note that not all AR-15s can be converted to use the .40 caliber round, so it's crucial to check compatibility before purchasing any parts.

The conversion process typically involves disassembling the upper receiver of your rifle and replacing the original components with those from the kit. Once installed, you'll be able to use .40 S&W ammunition in your firearm.

It's important to note that while this conversion may seem like an exciting upgrade for some gun enthusiasts, it might not always provide significant benefits over other cartridge options available for AR-platform rifles.

How does using a 40 cal AR-15 compare with other pistol-caliber carbines?

Using a 40 cal AR-15 offers several advantages over traditional pistol-caliber carbines (PCCs). For one thing, PCCs tend to be heavier than their counterparts since they require stronger barrels and receivers capable of handling high-pressure rounds.

By contrast, converting an existing lightweight rifle like an ar platform offers several performance benefits without increasing weight too much further beyond what one would expect coming from most handgun cartridges directly chambered in PCCs

Another advantage of using a converted ar platform is its accuracy at longer ranges compared with typical PCC’s which are often limited due mainly due their shorter barrels being unable maintain velocity past certain distance s .

However there are also disadvantages: Since these conversions aren't designed specifically for shooting handguns , recoil might also prove more difficult on smaller-framed shooters compared even pistols expressly made for firing higher pressure rounds such as Glocks or Sig Sauers.

Is it legal & how easy is getting hold of a conversion kit?

In general, owning and using a .40 cal AR-15 is legal in the United States. However, it's important to do your research before purchasing any parts to ensure that you're not violating any local or state laws.

The ATF has specific guidelines regarding what modifications can be made to firearms without changing their classification as rifles or pistols. These guidelines are complex and require careful attention when considering modifications like conversions on existing ar platforms even though they are granted status through the National Firearms Act (NFA)as short barrel rifles(SBR).

As for obtaining a conversion kit specifically designed for 40 caliber rounds , It may be easier said than done since these kits fall into NFA territory meaning some states might have restrictions about their sale & ownership .

How does shooting with 40 cal AR-15 feel compared with standard .223/5.56mm rounds?

Shooting with .40 S&W ammunition will feel noticeably different from firing standard rifle cartridges due mainly thanks its higher pressure as well as heavier bullet grains the resulting recoil force will likely surprise those familiar mainly only with lighter rifle rounds like .223s.

Firing one of these conversions an experienced shooter should expect more kickback & noise while also dealing shorter effective distances due heavier bullets losing velocity faster over range than traditional rifle cartridges

However, this trade-off is compensated by greater stopping power and penetration at short ranges which could make it attractive especially in tactical urban settings where engagement distances tend to be closer.

Can I convert my own AR-15 at home into 4o caliber?

While technically possible, converting an AR-platform firearm requires extensive knowledge of gunsmithing processes along with proper tools including specialized torque wrenches among others so it not something someone new would want try unless supervised by professionals.?

It’s worth noting that making such changes without appropriate licenses or training from industry experts can lead to serious injury if mistakes were made during installation increasing risk of malfunctions like a round becoming stuck in the barrel or even an explosion due to incorrect assembly.

It is always recommended that you take advice from industry professionals if you want to make these types of modifications on your firearm at home and not risk any mishaps. Additionally, many manufacturers sell complete uppers specifically built for use with .40 S&W rounds which might be more suitable than attempting to convert your existing platform into one capable of such use

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