AR-15 Caliber Comprehensive Reference Guide

The War Lock™ Multiple Caliber System was designed with the user in mind. This section will help to answer questions typically asked by AR-15 owners that would like to know what components they will need to complete their builds for specific calibers. If you have questions that are not answered here, please send them to us here.

The War Lock™ Multiple Caliber System works with mil-spec AR-15 platforms. To begin your build, you will need to provide either a complete mil-spec AR-15,or a complete lower receiver assembly for a mil-spec AR-15 (if you are using our completed upper receivers and barrel assemblies).

From this starting point, we provide different options.

The first option is the War Lock™ Multiple Caliber System as a kit. A kit is considered the most economical means to complete your multiple caliber builds. Installing the War Lock™ Multiple Caliber System yourself, and shopping around for the best prices for other components is a great way to reduce the cost of a multiple caliber build. Alternatively, the kit can be installed by a qualified gunsmith or armorer of your choosing.

Another option would be to purchase our complete upper receiver and our barrel assemblies with the War Lock™ Multiple Caliber System already installed. Coming soon! We will be offering this product for those that want to get right into shooting their multiple caliber AR-15.

Combinations of different options can also be used. Purchase a War Lock™ Upper (also coming soon) and build your own barrels, using the War Lock™ Barrel Adapter.

The War Lock™ Multiple Caliber System is a step forward in AR-15 modularity. The selection of available calibers is growing for your AR-15 every day. If you don’t see your desired caliber available on our site, contact us. We are adding new calibers constantly, and work hard to grow the selection.

AR-15 Caliber Comprehensive Reference Guide

Most caliber changes can be accomplished with a few simple component changes. The common components changed to switch between calibers on the AR-15 include the bolt, the barrel, and the magazine (and a magazine block for some). Some calibers will also benefit from switching between an adjustable gas block, buffer, and buffer springs. Many calibers only need one or two different components. You might be amazed at the ease in switching between calibers.

We understand that many customers want to build their own barrel assemblies in several different calibers. In order to assist you, we have provided a list of components for each caliber. This list assumes that you have provided your own mil-spec complete AR-15 lower receiver, War Lock™ Upper (either purchased complete, or installed) and one War Lock™ Barrel Adapter for each barrel assembly.

We try to make Frontier Tactical™ your source for most multiple caliber AR-15 products. We may not have every component needed for each build, so we include sources we have found that do carry the component you are looking for.

	Each caliber with a bullet icon indicates a supported caliber; or a caliber with sources for every component necessary for a complete build.
	The calibers with the Frontier Tactical™ compass icon are calibers that we have actually tested with the War Lock™ Multiple Caliber System.

Many calibers have been historically proven to work in an AR-15, but the companies producing the products were not successful in continuing production for common “off the shelf” purchase and use. Some have also used proprietary components that do not work with other systems. In some cases, the cartridges were made to perform through the AR-15 only after significant modifications to the AR-15 platform.

In most applications, for the War Lock™ Multiple Caliber System to work with a given caliber, the available components must be compatible with a mil-spec AR-15.

The calibers that do not have currently available components might still be utilized, as manufacturers add their own new products every year. Frontier Tactical™ is also working to produce our own line of products, and to work with other manufacturers to bring quality components into availability for over 60 different calibers.

Our comprehensive list was created to give an average AR-15 owner the information necessary to build barrel assemblies in multiple calibers without significant modifications, an average firearms understanding, AND with reasonable reliability. Many of the lesser supported cartridges require an above average understanding and skill in reloading. Re-sizing, fire-forming and other techniques for reloading brass is usually necessary for shooters wanting to try calibers that are not commonly supported.

Some AR-15 calibers can be purchased ONLY as complete uppers from a multitude of other companies. These calibers do not have a common source for the components (typically the barrel, bolt and magazine) that an AR-15 owner needs to build that caliber barrel for themselves. For this reason, the calibers requiring the purchase of a complete dedicated upper receiver are listed, but do not include our recommendation. They do not meet this list’s requirements for having enough currently available components to support the common use of this cartridge through the AR-15 platform. That should not discourage the AR-15 owner from considering any of the calibers listed.

Links to third-party sources will navigate you away from this list. Frontier Tactical™ is not affiliated or liable for information or products not provided directly from our company and website.

CALIBERS FOR THE AR-15

METRIC PISTOL CARTRIDGES
Supported Caliber	Tested	Caliber	Description
		FN 5.7×28mm	This cartridge has not been tested with the War Lock™. It will probably NOT work with our adapter. The FN 5.7x28mm commonly uses a different upper receiver.
		7.62×25mm Tokarev	This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.
		9×19mm Parabellum	This cartridge requires a properly chambered barrel and bolt in 9x19mm, a 9x19mm buffer, magazine block and 9x19mm magazine. This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.
		9×21mm	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The 9×21 (or 9mm IMI) was designed for markets (primarily outside of the U.S.), where civilians are restricted from purchasing “military” cartridges. Significant sources for 9×21 AR-15 components are highly uncommon.
		10mm Auto	This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.

STANDARD PISTOL CARTRIDGES
Supported Caliber	Tested	Caliber	Description
		.30 Luger (7.65x21mm, 7.65 Parabellum)	This cartridge requires a properly chambered barrel in .30 Luger,  a 9x19mm bolt, 9x19mm buffer, magazine block and 9x19mm magazine. This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.
		.357 SIG	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The .357 SIG enjoyed limited popularity (primarily in pistols), but industry support for this cartridge is waning. Significant sources for .357 SIG AR-15 components are highly uncommon.
		.40 S&W	This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.
		.400 Corbon	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The .400 Corbon utilizes many of the same components as the .45 ACP. Significant work would be required to use this cartridge in the AR-15. Most notably would be sourcing a .400 Corbon barrel.
		.41 Action Express	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The .41 AE was designed to provide .41 Magnum performance out of semi-automatic pistols, but industry support for this cartridge was mostly ignored by manufacturers that backed the .40 S&W cartridge.
		.45 GAP	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The .45 GAP enjoyed limited popularity (primarily in pistols), but industry support for this cartridge is waning. Significant sources for .45 GAP AR-15 components are highly uncommon.
		.45 Super	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Although the .45 Super is ballistically superior to the venerable .45 ACP cartridge, industry support has not yet provided significant component sources for the AR-15 platform.
		.45 ACP	This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.
		.45 Winchester Magnum	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The .45 Winchester Magnum has no parent case (typical of other .45 caliber cartridges). Since it is “unique” as a cartridge, it’s support is very limited. AR-15 use is nearly non-existent; with it primarily being used by hunters and competition shooters.
		.50 Action Express	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The .50 AE enjoyed brief popularity within the AR-15 community. Due to availability limitations on parts and ammunition, most AR-15 owners and manufacturers have transitioned to the .50 Beowulf cartridge.

METRIC RIFLE CARTRIDGES
Supported Caliber	Tested	Caliber	Description	Reference/Purchase Link
		5.45×39mm	This cartridge requires a properly chambered barrel and bolt in 5.45x39mm and a 5.45x39mm magazine. This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.	Click Here
		5.56×45mm NATO	This cartridge requires a properly chambered barrel and bolt in 5.56x45mm NATO and a 5.56x45mm NATO magazine.This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.
		6mm TCU	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform.	Click Here
		6×45mm	This cartridge requires a properly chambered barrel in 6x45mm and a 5.56x45mm NATO bolt and magazine. This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.	Click Here
		6×47mm	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform.	Click Here
		6mm AR	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform.	Click Here
		6mm AR Turbo 40˚ Improved	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform.
		6mm PPC	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The 6mm PPC cartridge is primarily used for benchrest shooting. Use of this caliber would likely require reloading or hand-loading the ammunition.
		6mm Whisper	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The 6mm Whisper is less common than other 6mm cartridges for the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		6mm WOA	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The 6mm WOA is less common than other 6mm cartridges for the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		6mm Hagar	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform.	Click Here
		6mm BR Remington	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. The 6mm BR uses a .473 bolt which at this time is proprietary.
		6×6.8	This cartridge has not been tested with the War Lock™. The 6×6.8 cartridge is significantly easier to reload than many of the other 6mm AR-15 cartridges.	Ammo | Barrel
		6.5mm Whisper	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		6.5mm Grendel	This cartridge requires a properly chambered barrel and bolt in 6.5mm Grendel and a 6.5mm Grendel magazine (a 5.56x45mm NATO magazine will work, although with decreased capacity).  Alternatively, the .264 LBC barrel with a Type I chamber can fire this cartridge with the 7.62x39mm bolt.  Bolt depth of .125″ required, with the matching chamber.This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.	Click Here
		6.5mm PPC	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		6.5 WSSM	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		6.5 WOA	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		6.5×6.8	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.	Click Here
		6.8mm Remington SPC II	This cartridge requires a properly chambered barrel and bolt in 6.8mm Remington SPC II and a 6.8mm Remington SPC II magazine. This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.
		7mm Whisper	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		7mm TCU	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		7.62×39mm	This cartridge requires a properly chambered barrel and bolt in 7.62x39mm and a 7.62x39mm magazine. This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.	Brownells | AMMOSC

STANDARD RIFLE CARTRIDGES
Supported Caliber	Tested	Caliber	Description	Reference/Purchase Link
		.17 Practical	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.17 Remington	This cartridge requires a properly chambered barrel in .17 Remington, a .223 Remington bolt and magazine.This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.	Click Here
		.17-223	This cartridge requires a properly chambered barrel in .17-223, a .223 Remington bolt and magazine.This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.	Click Here
		.17 HMR	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.17 HM2	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.17 WSM	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.204 Ruger	This cartridge requires a properly chambered barrel in .204 Ruger, a 5.56x45mm NATO bolt and magazine. This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.	Click Here
		.20-6.8	This cartridge has not been tested with the War Lock™. The .20-6.8 cartridge is difficult to find information for. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.	Click Here
		.20 LBC	This cartridge has not been tested with the War Lock™. The .20 LBC cartridge is one of the more labor intensive cartridges with regard to reloading/hand-loading the ammunition. It should not be considered a “beginner” caliber.	Info | Barrel
		.20 Tactical	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.20 Practical	This cartridge requires a properly chambered barrel in .20 Practical, a 5.56x45mm NATO bolt and magazine. This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.	Click Here
		.20 VarTarg	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.22-6.8	This cartridge has not been tested with the War Lock™. The .22-6.8 cartridge is difficult to find information for. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.	Click Here
		.221 Fireball	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.22 LR	The most economical conversion for this cartridge requires only a drop in bolt carrier and a .22 LR magazine.This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.	Click Here
		.22 WMR	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.222 Remington	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.222 Remington Magnum	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.223 Remington	This cartridge requires a properly chambered barrel and bolt in either .223 Remington or 5.56x45mm NATO and a .223 Remington or 5.56x45mm NATO magazine.This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.
		.223 Remington Ackley Improved	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.223 WSSM	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.243 LBC	This cartridge requires a properly chambered barrel and bolt in .243 LBC and a 6.5mm Grendel magazine (a 5.56x45mm NATO magazine will work, although with decreased capacity). This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.	Click Here
		.243 WSSM	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.25 WSSM	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.25-6.8	This cartridge has not been tested with the War Lock™. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option. The .25-6.8 cartridge is difficult to find information for.	Info | Barrel
		.25-45 Sharps	This cartridge requires a properly chambered barrel in .25-45 Sharps, a 5.56x45mm NATO bolt and magazine.This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.	Click Here
		.264 LBC	This cartridge requires a properly chambered barrel in .264 LBC, a 6.5/.264 LBC bolt and magazine. The .264 LBC cartridge appears to have been designed and brought to the market in response to the confusion within the 6.5mm AR-15 community.  A Type I barrel allows the operator to utilize a 7.62x39mm bolt to fire .264 LBC or 6.5mm Grendel cartridge.  Bolt depth of .125″ required, with the matching chamber. This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.	Click Here
		.30 Remington AR	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.300 Whisper	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.30 Herrett Rimless Tactical	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.300 AAC Blackout (7.62×35mm)	This cartridge requires a properly chambered barrel in .300 AAC Blackout, a 5.56x45mm NATO bolt and magazine.This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.
		American 30 BHW	This cartridge requires a properly chambered barrel in American 30 BHW, a 6.8 Remington SPC II bolt and magazine (a 6.5 Grendel magazine should also work). This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.	Click Here
		.300 OSSM	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.30 Carbine	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.35 Gremlin	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.358 WSSM	This cartridge has not been tested with the War Lock™. We have not found enough currently available components to support the common use of this cartridge through the AR-15 platform. Use of this caliber would likely require significant effort and education for the enthusiast wanting this option.
		.375 SOCOM	This cartridge requires a properly chambered barrel in .375 SOCOM, a .450 bolt and magazine.This cartridge has not been tested with the War Lock™. It SHOULD work with our adapter. We will be testing this cartridge to be used with the War Lock™.
		.450 Bushmaster	Use of this cartridge in the AR-15 typically requires enlarging the ejection port hole to allow clearance for the larger cartridge. This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.	Click Here
		.458 SOCOM	Use of this cartridge in the AR-15 typically requires enlarging the ejection port hole to allow clearance for the larger cartridge. The .458 SOCOM was designed to be compatible with the standard AR-15 platform. It utilizes the same buffer, buffer spring, steel G.I. magazines, and lower receiver.This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.
		12.7x42mm ( .50 Beowulf)	Use of this cartridge in the AR-15 typically requires enlarging the ejection port hole to allow clearance for the larger cartridge. The  12.7x42mm (.50 Beowulf) cartridge uses a 7.62x39mm AR-15 bolt.  It utilizes the same buffer, buffer spring, steel G.I. magazines, and lower receiver.  Bolt depth of .125″ required, with the matching chamber. This cartridge has been tested with the War Lock™. It DOES work with our adapter. Frontier Tactical™ sells most of the components necessary for complete assemblies or “do it yourself” builds.

Our AR-15 Caliber Quick Reference Guide can be found here.

Frontier Tactical™ has worked hard to provide the most comprehensive list anywhere. We cannot cover every possibility, and look forward to suggestions and feedback to improve this list. Please contact us here with any calibers we should add or update.

We hope this information was helpful. Our goal was to provide a user’s guide for anyone who wondered what changes or conversions are necessary to fire specific caliber cartridges through an AR-15.

Let us know if this is a valuable resource for you in the comments below.