Stern Defense makes great AR magazine well adapters which turn your AR Lower into a Pistol Caliber Carbine. The version that caught my eye uses S&W M&P .45 ACP mags. Mag-AD series adapters install in seconds, just like an AR magazine. They have a separate magazine release at the bottom you manipulate with your trigger finger and a functioning last round bolt hold open feature.

As Graham Baates says, “In 2018, everybody who wanted an AR has five.” Many of you reading this have stripped AR lowers in the closet that you never built because you had all the .223 action you needed. Here is the excuse to build the pistol caliber AR you always wanted. If you only have one AR, in one minute, you can change the upper, buffer and add a magwell adapter. Boom, new gun.

Pistol caliber ARs are cheap plinkers and great training tools perfect for new shooters. You can safely shoot handgun steel and use the magazines you already have. Law Enforcement agencies can build an AR that accepts their duty pistol mags for the ultimate police patrol rifle.

Turn Your AR Lower into a .45 Pistol Caliber Carbine: Stern Defense
.45 Pistol Caliber Carbine: Stern Defense 1

I have worked several AR conversion systems, but nothing like the Stern Defense .45. I got their MAG-ADMP45 conversion kit, with adapter, complete .45 caliber upper and their 11 ounce carbine buffer. These adapters require the use of a 45ACP barrel, and a Glock cut bolt. You can buy the bolts and barrels from Stern separately.

Safety Notes:

45ACP UPPERS MUST ALSO HAVE AN ENLARGED EJECTION PORT.
CLICK HERE FOR UPPER
,

THIS UPPER MUST BE USED WITH A 11 OUNCE BUFFER OR HEAVIER WHEN USING A CARBINE SPRING. CLICK HERE FOR BUFFER

Turn Your AR Lower into a .45 Pistol Caliber Carbine: Stern Defense
.45 Pistol Caliber Carbine: Stern Defense 2

The big question; Do they work? When I got my kit, I built as a pistol on an AR lower with a rounded hammer. I read the instructions and adjusted the three screws. The adapter was locked up tight. I oiled the bolt, checked it with a magazine, threw in the 11oz buffer and cycled some dummy rounds. This was too easy, I was wondering if I was doing things right. Everything went right together and cycled perfectly.

Off to the range, I have put 250 rounds of .45 ball and JHP through it so far with no jams and no issues. The Stern adapter fits snugly and it runs smoothly using S&W factory extended magazines. The magazines drop free and the bolt hold open works.

Turn Your AR Lower into a .45 Pistol Caliber Carbine: Stern Defense
Muzzle brake on the .45 Pistol Caliber Carbine: Stern Defense

The handguard is light and dissipates heat well. The muzzle brake looks great with the flush esthetic that I prefer. It has a conical profile on the inside which effectively focuses the blast forward toward the target

The recoil is effectively managed with the heavy buffer. I wouldn’t even think about .45 with anything lighter. The recoil is more than .223 but less than 12 gauge. It is very manageable and not unpleasant.

I am going to shoot this gun, a lot more. I was so excited when I got it, I literally threw it together, grabbed ammo and sped to the range. I wanted to tell you about it. I will write another review after 1000 rounds.

This excellent Stern Defense video shows the 9mm kit, installation and full auto firing.

If you are building a gun from parts instead of the Stern conversion kit, there are many parts common to the AR. In addition to a complete lower with an oversized 11 oz buffer, you have to select the correct upper, bolt and barrel to make these guns run.

Turn Your AR Lower into a .45 Pistol Caliber Carbine: Stern Defense
.45 Pistol Caliber Carbine: Stern Defense 3

Because there is no MILSPEC for .45 ARs, each manufacturer makes them a little differently. If you buy everything from the same place, you chances of an easy build like mine are much higher. Maybe you will be lucky. How ever you decide to get there, now you don’t have to build a dedicated lower. Stern has a web page you can check before purchasing to ensure compatibility with your setup so you don’t buy parts that don’t fit together.

Turn Your AR Lower into a .45 Pistol Caliber Carbine: Stern Defense
45 Pistol Caliber Carbine: Stern Defense 5

The pistol pictured above has the MAG-AD9 W/ MOD5 10” M-LOK 8.5”BARREL 45ACP PISTOL UPPER KIT MSRP $695.49

The 11 ounce heavy buffer is vital for .45 systems and works great with smaller calibers. It not only reduces felt recoil, it allows for reliable function on pistol caliber AR systems. MSRP $56.00

The Stern MAG-ADMP45 series adapters are made of aircraft grade aluminum, lightweight with ergonomic design. There is a tension adjustment feature to eliminate wiggle.

Turn Your AR Lower into a .45 Pistol Caliber Carbine: Stern Defense
The Stern Defense MAG-ADMP45 use 45ACP M&P Magazines

Technical Information:

⦁    Made in the U.S.A.

⦁    Constructed from 6061 T6 aircraft grade aluminum.

⦁    4140 NiB coated feed ramp.

⦁    Hard coat anodized type 3.

⦁    Sturdy Construction.

⦁    Ergonomic mag release.

⦁    Works with any mil spec ar15 lower receiver.

⦁     All lower components besides the adapter remain stock

 

This is what plugs into your magwell. You can see the magazine release sticking out to the left.

 

 

Turn Your AR Lower into a .45 Pistol Caliber Carbine: Stern Defense
.45 Pistol Caliber Carbine: Stern Defense 6

These adapters are very sophisticated. They lock in hard with no wiggle after adjustment. They hold your mags in and drop them free. The bolt hold open works every time.

The Stern Defense bolts are high quality and have the mass to safely and reliably run direct blow back pistol caliber carbines. They look great.

Turn Your AR Lower into a .45 Pistol Caliber Carbine: Stern Defense
.45 Pistol Caliber Carbine: Stern Defense bolt

They also make a nifty extended polymer magwell that clamps on and speeds up reloads.

Turn Your AR Lower into a .45 Pistol Caliber Carbine: Stern Defense
Stern Defense magwell flare

Stern Defense makes AR PCCs great again. Stern has all the parts you need to turn your AR Lower into a Pistol Caliber Carbine. There are several versions available which accept Glock magazines (9mm/.40), Beretta magazines (9mm), two S&W M&P magazine versions in (9mm/.40 and .45 ACP).

Want to see their other conversion kits? Click Here.

Bolts? Click Here

Barrels?  Click Here

You can get your very own Stern Defense Magwell .45 Adapters HERE. MSRP $186.99

Other models available as well.

About Stern Defense:

STERN DEFENSE is a family owned American specialty manufacturer committed to precision, quality, and efficiency of the weapon accessories created. They use the best USA supplied material our products are designed and manufactured by the finest machinists and engineers in the industry.

Stern Defense Magwell Adapters: Turn Your AR Lower into a Pistol Caliber Carbine
The family behind Stern Defense

Their values? Traditional, Rooted, Firm and STERN.