Hello and welcome back to another edition of The Rimfire Report! This ongoing series is all about the rimfire firearm world and its various guns, gear, ammunition, and sports! Last week we took a look at the much loved CCI Velocitor 40-grain 22LR cartridge to assess its efficacy as a self-defense cartridge when being fired out of a pistol. What we saw and what many of you could have guessed is that the hypervelocity 40-grain hollow points didn’t really perform all that well out of the shorter barrels, but once up to speed out of the longer barrel of my Ruger 10/22, they expanded aggressively and also penetrated to an adequate depth! Interesting stuff! Speaking of Ruger firearms, I recently came across this interesting upper for the MKIV pistol manufactured by MaddMacs Precision Tactical LLC – the MK4 Carbine. I’ve always dreamed of working out a way to turn my MKIV pistol into a lightweight carbine and while there might be some hokey homemade options out there, this is the first time I’ve seen one made by a reputable manufacturing company and it looks not only well made but opens up a lot of possibilities to turn your MKIV pistol into a more well rounded and lightweight backpack gun. Today we’ll be checking out the features of this upper and make a few comments on its design and how I think it could be used in various applications.

More Rimfire Report Articles @ TFB:

• The Rimfire Report: CCI Velocitor As A 22LR Self-Defense Cartridge?
• The Rimfire Report: Review of Federal Punch 22LR Personal Defense Ammunition
• The Rimfire Report: How 3D Printing Saved My High Standard Flite King

Photo: MaddMacs Precision

The Rimfire Report: Pondering the MK4 Carbine from MaddMacs Precision

So what exactly is the MK4 Carbine? As you can suspect, it is a whole firearm designed around the Ruger MKIV pistol. The Ruger MKIV is an extremely popular rimfire pistol that is great for a number of tasks but mostly finds itself being used as a trainer, squirrel hunter, and competition gun. The MaddMacs MK4 Carbine takes your unserialized MKIV lower and combines it with their MK4 Carbine upper turning it into a new package deal that has not only Picatinny rail space on top, but also a 1/2×28 threaded barrel, and a mil-spec carbine buffer tube which allows the use of commonly available stocks like the Magpul MOE stock. The carbine was made by a joint venture between MaddMacs Precision Tactical LLC, and competitive shooter Wade Reed. Wade Reed designed the upper specifically to integrate with the MKIV pistol and reached out to MaddMacs Precision to produce it at first for himself but it is now being offered as a complete upper/firearm for regular joes like you and I.

Photo: MaddMacs Precision

Right off the bat, I find this kind of setup to be extremely appealing. For one, the MKIV pistol is very easy to clean by virtue of its simple one-button takedown system and for any high volume of fire rimfire gun, I think it’s a neat addition. It also means that swapping your MKIV pistol to the MK4 Carbine is a simple task. 22LR cartridges often don’t get their full performance out of shorter barrels and having the 16″ .900 OD barrel there means that you’ll be getting better velocities out of your ammo and in a survival or backcountry hiking kind of scenario this also means you’ll have an easier time hunting game animals with your new carbine.

Photo: MaddMacs Precision

The MK4 Carbine starts off at a price of 849.95 and will require it to be transferred to your FFL, and you’ll also need an MKIV lower to host the upper. There are a handful of other more expensive options with different features that we’ll mention below too. From what I’ve heard, there is already a significant wait time for these carbines so if you’re interested in buying one, sooner rather than later might be a good choice.

Uses for the MK4 Carbine

First on my list is plinking. All rimfire guns are plinkers but not all rimfire guns do things other than plinking equally. Given that the MK4 Carbine weighs just an ounce under 3lbs (2lbs 15oz), I think it would make a great trainer for a newer or younger shooter. Since the carbine incorporates a ambidextrous side charging handle, the new shooter will also be able to easily charge, unload, and safe the carbine while still using their shoulder as support.

Photo: MaddMacs Precision

Another immediate use I think I would probably gravitate towards is as a competition gun, specifically for steel challenge in the RFRO (Rimfire Rifle Open) division. The lightweight gun should make for very smooth transitions between targets and since the MKIV is already super reliable, this lightweight carbine should give you a competitive platform without spending thousands on some of the higher-end 10/22 receivers, stocks, and muzzle accessories to make a competition rifle.

Photo: MaddMacs Precision

One drawback you might run into, however, when it comes to a high volume of fire days is the barrel’s heat. The .22LR isn’t known for heating up barrels too much, especially bull barrels, but with a combination of summer heat and hundreds of rounds fired in a short amount of time, you might find yourself holding onto a hot stick with your support hand. For that, however, MaddMacs has the MK4 Carbine CF and the Bantam. Both of these carbines not only have parts that lend themselves better to insulating your hand from any generated barrel heat, but they also weigh much less than the standard MK4 Carbine and come in at nearly 2 pounds even.

Why No Folder?

When I initially saw the MK4 Carbine, the first thing I wanted to do (besides buying one) was add a Law Tactical folder to it. I think the addition of one of these folders combined with perhaps a shorter barrel (MaddMacs does make a 12″ barrel for the carbine but it features a pinned and welded shroud to make it 16″ OAL) would make this the perfect backpacking gun allowing you to collapse the entire rig down to fit neatly inside a day pack with plenty of room for spare magazines and ammunition.

This would put the MKIV pistol (or carbine) on par with the portability and convenience of one of Henry’s AR-7 Survival Rifles but would have the additional benefits of being easier to deploy, and having larger magazines. I can’t speak to the MK4 Carbine’s reliability or construction quality as I have yet to handle one myself, however, if properly assembled and quality controlled, I don’t see any reason why the carbine shouldn’t perform as well if not better than a standard MKIV pistol would – just with the added stability of a stock and longer barrel.

All I really aimed to do today was share this unique rimfire rifle with you guys and as always I’d like to hear your thoughts, comments, and opinions on the MK4 Carbine from MaddMacs Precision. If I can find the funds and time, I’d really like to get my hands on one of these and test it out during a Steel Challenge competition and also test it for accuracy and reliability. Thanks as always for reading TFB and The Rimfire Report! We’ll see you all next week!

Big thanks to Maddmacs and Wade Reed for allowing TFB to use their pictures for this article. Be sure to check them both out!