Frankenstein AR-15s: Are They Worth the Money?

Terms like custom-built, upgraded, modified, and Franken AR-15 rifles are all used to describe some type or version of an AR. While a Franken gun has different meanings to different people, most all would agree that it’s not an off-the-shelf rifle.

I have always viewed a Franken gun as one assembled from various parts and therefore, not a brand-name rifle. To some, this would be a custom-built gun if the build resulted in a quality rifle. If it resulted in a low-quality, unreliable rifle, they would call in a Frankenstein gun. Others also apply this term to a stock rifle that’s been modified extensively.

Custom built AR-15 pistol.
I’ve built serval ARs over the years with random parts acquired over time. [Photo: Jason Mosher]
I’ve included a list of terms below that break down the meaning of each one. Again, this may be different from others, but it’s what I have heard the most over the years. Using those terms, the one I want to focus the most on today is the Frankenstein gun. Some would ask if it’s worth the trouble and if there are any positive or negative aspects of it. I hope to cover those topics today. Let’s get to it!

AR-15 terms according to no one in particular

  • Stock AR-15: A complete rifle purchased from a retail store. May still need accessories like sights, red dot, flashlight, etc.
  • Custom Built AR-15: A rifle built using quality, and mostly matching parts. For example, buying everything from Aero Precision to build a complete AR-15 would be a custom-built Aero Precision rifle.
  • Frankenstein AR-15: A completely assembled AR-15 using parts from multiple manufacturers.
  • Upgraded AR-15: A stock AR-15 with some type of enhanced part that does not change the overall makeup of the gun. This could be an upgraded trigger, stock, muzzle device, etc.
  • Modified AR-15: Any type of AR-15 that has been changed from its original configuration to perform differently. This could include swapping out a 5.56mm barrel for a 300 blackout or adding a folding stock.

Building a Franken AR-15

Using this term makes me think of a weird-looking gun with parts bolted and welded in various places. This is one of those guns you wouldn’t fire if someone paid you. Sometimes that may be the case, but you can have a high-quality or low-quality gun, regardless of the term. One of the examples I’m using today is a favorite of mine. It’s a project I started several years ago that progressed into an AR-15 pistol that shoots like a dream at the range.

Custom built AR-15 pistol.
When you build your own AR-15, you can make it into exactly what you want. [Photo: Jason Mosher]
This one is a good example of a “Frankenstein” build because every part of it came from different companies. I did order quality parts, so calling it a Frankenstein gun will depend on each person’s view of that term. This wasn’t even a planned project, but the lower receiver was on sale, and I couldn’t say no. More parts were found later and before I knew it, I had the following list of parts:

  • Geissele Super Duty lower receiver
  • BCM upper receiver
  • Ballistic Advantage 8” barrel
  • Timber Creek Enforcer pistol grip
  • CMMG lower parts kit
  • Black Rain extended charging handle
  • Fail Zero BCG
  • Maxum Defense telescoping pistol brace

Once it was built, I put an EOTech 512 holographic sight and Holosun LS117R laser on it. The gas tube was in my parts box, and I couldn’t even tell you what brand it was. Most of these items were purchased on sale at various times over two years. I’m estimating I have about $1,000 in the AR pistol and another $700 in the optic and laser.

What is the benefit?

Here is where there will be many different opinions from everyone who has ever owned or built an AR-15. But this question really depends on several factors including overall quality, personal preference, and price. Would I be able to sell this gun with accessories for $1,700? Maybe or maybe not. When it comes to quality it really depends on the parts used and proper installation. I’ve put more than 1,000 rounds through this gun, and it’s never had one malfunction.

But I have mixed different upper and lower brands before and had some issues. So, some of it comes down to finding parts that fit together well. I like to build my own AR-15 rifles for several reasons. One reason is that I can build the gun to look and feel exactly how I want. Another reason is that it’s easier on the wallet to buy quality parts on sale when you find them. Buying a stock rifle is great if you have the money all at once.

AR-15 pistol, is it a Frankenstein gun?
The term used for an AR built from different brands of parts is often referred to as a “Franken” gun. [Photo: Jason Mosher]
The last reason I like to build my own rifles is because I enjoy it. Buying a stock gun that’s ready to go is great and I do that from time to time as well. But I just like the slow process of looking for parts and building the gun once I have what I want. From this aspect, it’s not about saving money or building a “better” gun. The reason to build one will be different for each individual person.

Custom Build vs Frankenstein

Again, these terms are used very loosely so I’m going off what I’ve grown up with as it relates to terms. Regardless of what you all it, the question is are there benefits to buying all parts from the same company? For example, I built a Wilson Combat rifle using all Wilson Combat parts. How is this different than my Franken gun? The WC build will retail for more because everything on it is branded and matching. The only real difference between my WC and a stock rifle is I bought the parts and assembled it myself.

I can’t really call the other one by a “brand” name because there are too many other parts on it. The receiver is a Giessele product, but it’s not a true Giessele AR. I have just as much faith in both rifles on the range and they both perform great. But the Wilson Combat will always have a little more retail value because it’s not an assortment of different parts.


If you want to build your own AR-15, then build one. If you have never built one before, make sure you do your research and obtain the necessary tools. It doesn’t matter if you call it a Franken AR, custom build, or a criminal deterrent device. What matters is that it functions safely and correctly. Beyond that, you can make it whatever you want.

Buy one, build one, or customize one, there isn’t really a “best” way. Many off-the-shelf AR-15s are made from stock parts consisting of multiple brands. I like my stock AR-15s and my builder’s Wilson Combat AR, but I also like my Frankenstein gun. It shoots great, it’s reliable, and it’s exactly what I wanted it to be.

Sheriff Jason Mosher is a law enforcement generalist instructor as well as a firearms and tactical weapons trainer. Jason graduated from the FBI-LEEDA (Law Enforcement Executive Development Association) and serves as a Sheriff for his day job. When he’s not working, he’s on the range, eating steak, or watching Yellowstone.

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