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I've always liked the concept of a bullpup, but the fact that I'm left handed and most bullpups have a lot of issues meant I could never choose any existing bullpup over an AR-15. I still like the weight distribution and ergonomics, but that was limited to playing around at the range. For many years eagerly waited for the gun industry to make a bullpup that addressed all these issues. I had high hopes for Desert Tech, since their bolt actions are very good, but I found the MDRX/WVRN to be disappointing. Eventually I got tired of waiting, and I decided to design one myself.

I looked through some drawings I had made back when I was in college, almost 10 years ago. Back then I had just got into guns as a hobby, and had neither the time nor funds to follow through with the design. Since then my gunsmithing skills have improved significantly and I updated my design with the following features:

Downward ejection:

I placed the ejection port on the bottom of the lower receiver, behind the magazine. This solves the left handed issue. The problem with the design where you can switch the ejection side is sometimes you want to shoot with your off hand when you're going around a corner, and there isn't enough time to break out tools to change it. Having it eject down satisfies all use cases.

The placement of the ejection port also eliminates gas blowback when using a suppressor. Because the new position of the ejection port can no longer be used to clear jams, an additional cut is added on the top of the upper receiver that is covered by the non-reciprocating charging handle when firing. When the charging handle is pulled it will automatically open. This port is large enough for a multitool, and can also be used to check if the weapon is loaded.

Because the bolt carrier needs to travel twice its own length, the rifle will have reduced recoil as a consequence of the lower cyclic rate and constant recoil, which is a feature found in the Ultimax machine gun and the Knights Armament LAMG.

Use of AR-15 and AR-10 bolts and barrels:

I decided to use AR-15 and AR-10 pattern bolts and barrels because they are the most common, and easy to find both in person and online. This opens up the end user to take advantage of the numerous barrel profiles, and chamberings found for the AR platform. The barrel and bolt are also the fastest wearing parts, so I wanted to avoid designing a proprietary barrel extension to make maintenance easy.

Another big reason was to make the rifle more attractive for military adoption. Since most Western militaries are already using weapons derived from the AR-15, they will have lots of barrels in storage that can continue to be reused. This will make logistically supporting this weapon easy, which is an often overlooked, but extremely important consideration in warfare.

AR-15 pattern controls:

It was extremely important to me to have the controls as close to the AR-15 as possible, which have become almost standard. This eliminates the need to retrain muscle memory, and allows for quick manipulation of the rifle. As a southpaw, I made sure all the controls were not just ambidextrous, but the same and both sides. Many bullpups will overlook the bolt catch and magazine release linkages, such as the Steyr AUG. In my opinion this is a huge reason why most bullpups fail.

Drop in magwells:

By making the magwells drop in, with hooks in the front, the rifle has functional linkages with a wide range of magazines, not just AR-15 and SR-25 STANAG pattern magazines. If people want to use AK magazines, SCAR magazines, or even FAL magazines, that is possible in the future. By having a common interface for he magwell footprint and hooks, all of these magazines will have functional magazine release and bolt catch forward linkages.

Drop in fire control module:

Most bullpups have very heavy and sluggish triggers. I have done my best to fix both of these problems, but I decided the best way to ensure that the trigger can be easily improved over time is by making the fire control system a drop in module. This makes it easy to convert to a select fire system or a specialty match grade trigger.

Ejection port accessory module:

Initially I wanted to make a snap in interface for a brass catcher, but I decided to use that same interface for the dust cover as well. Not everyone needs a dust cover, so by not making it part of the rifle itself the cost to manufacture is lowered. Now, both the dust cover and brass catcher can be improved over time, and the aftermarket can create accessories that I could not think of.

Free float handguard and short stroke gas piston:

Free float handguards are expected on any modern precision rifle, and this is a feature that many bullpups lack. The MBAR is free float, so the accuracy is limited to the quality of the barrel. Short stroke gas pistons are pretty much standard now. When the AR-15 was design suppressors were not in widespread use, which is probably why the direct impingement system was chosen. Piston systems are generally less accurate and have more recoil than direct impingement systems, but are much better at handling heat and operating while suppressed. Long stroke systems such as the one the X95 and AKs use have much greater recoil and are less accurate than both short stroke systems and direct impingment, so I felt a short stroke system was a good compromise.

I designed this rifle to be as modular as possible. As an engineer, we are always encouraged to design something to be re-used in as many situations as possible, because designing new parts requires a lot of time and effort to test properly. After some consultation with friends I decided to name this rifle the Modular Bullpup Automatic Rifle or MBAR.

My plan is to build a prototype and license it to an established manufacturer for production. I have filed patents with the US Patent and Trademark Office, as well as the European Patent Office. However to ensure there is a large aftermarket for spare parts, I will not be enforcing the patents on the accessories (such as the magwell, fire control module, ejection port accessories, and gas block), and will license out other parts production generously. I realize that the aftermarket is one of the reasons for the AR-15's success, and I want to encourage development on this platform. Furthermore I will be releasing a lot of 3d files for this rifle, so people can make some parts at home. In the event of parts breaking, a replacement can be quickly 3d printed.

If you are interested please subscribe to my Youtube channel where I have more detailed breakdowns of the internal mechanism.