Building an Imbel FN-FAL from a parts kit

By way of setting up this story I thought I'd give a little background. I like to collect military rifles. I also like to rebuild and build them. The FN-FAL has been called the assault rifle of the free world. I didn't have one so this project was born.

Early last year I bought a metric pattern Imbel FN-FAL parts kit that is believed to have come from Chile. It is one of those rifles that looks like it has been carried a lot, but fired little. Parts and bore look very good. The finish is unimportant since I will completely refinish it.

I've waited about 6-7 months to get a DS Arms upper receiver to complete the rifle. Research suggested that DSA made the highest quality receivers. I ordered mine with a cut for the carry handle. Yesterday I finally got my upper receiver. FFL Russ Fritz of Ft. White, Florida handled the transfer for me.

So, here is what I have.

The major parts.


An idea of what the rifle will look like when assembled.


Notice the rear of the barrel has a piece of the original receiver attached and will have to come off so the new receiver can be installed.




Here is where the upper receiver attaches to the lower receiver and butt stock.


What would an assault rifle be without a bolt, bolt carrier, charging handle and dust cover?


There is a lot of work ahead of me. I'll continue to post here and update the project. This should be fun. To be legal in the US this rifle will have to contain 7 parts made in the US. For this build those parts will be something like receiver, gas piston, hammer, sear, trigger, SAW pistol grip and  furniture from Gun Parts Guy.

Next I chose to remove the old nub of a receiver from the barrel. This isn't my idea, I'm not that clever. I saw it done on a video tape made by the Gunplumber.

I clamped the receiver end of the barrel in a padded vice and got out a Dremel Tool with a cut off wheel. There is an indentation along one side of the old receiver and that is where I used the Dremel Tool to cut a groove front to back on the old receiver. The intention is to cut the groove deep enough to just about touch the barrel threads. Easy does it here. You can tell when you are deep enough. You will see the tips of the barrel threads if you go deep enough. The video said if you nick the barrel threads it doesn't matter. Your face will be close to the work to do this. Wear safety glasses. I had 4 cut off wheels fly apart doing this.

Dremel cutting groove along receiver.


When the groove has been cut get a big ass cold chisel and a big ass ball peen hammer and drive the cold chisel into the end of the receiver nub where you cut the groove and hit that chisel good and hard. Maybe a few times. Suddenly the old receiver splits right down the groove you cut and spreads slightly. Cold chisel tip is on the right. Cleaning rod points to the groove which has a very nice split right along it.


Clamp the barrel flats in the padded vice and grab the receiver nub with a wrench and unscrew it from the barrel. It came off quite easily. I used a big crescent wrench. I imagine you can use a pipe wrench. The nub is a throw away part.


The old demilitarized receiver nub is off the barrel without a mark on the barrel or threads.


This was the toughest job I am supposed to encounter in disassembling the FAL. It was easy.

The original barrel screwed into the new DSA upper receiver by hand. I would screw it in a short way and back it out a bit and repeat until it screwed all the way in and stopped against the receiver. After the first time the parkerized coating was chased off the receiver threads and the barrel screwed in and out with ease.

Here is an important part of the project. Barrel timing. When the barrel is finally screwed into the receiver and tightened the front sight has to be vertical. You can imagine the results if the front sight leaned to one side or the other, not to mention the gas tube and piston wouldn't align.

There is a small rounded notch on the barrel. It should line up at the 11:00 o'clock position when screwed in tight by hand. The 11:00 o'clock position is defined by an imaginary triangle at the base of the the gas tube port on the receiver. Then when the barrel is torqued down the front sight should be lined up vertically.

In the photograph the brass punch is pointing to the rounded notch on the barrel. The picture is dark so take a close look for it.

The pencil points to the imaginary triangle at the base of the gas tube port.

As you see, my barrel notch lines up at the 10:00 o'clock position. This means the mating shoulder at the base of the barrel will have to be turned down on a lathe just enough to index the barrel notch at the 11:00 o'clock position against the receiver. Russ Fritz will do the machining this Saturday.

I took my barrel and receiver to the machine shop of gunsmith Russ Fritz so he could do the machining needed to time the barrel to the receiver. Russ had his big lathe pretty much set up and waiting for my job.

Perhaps one thousandth of an inch had to be removed from the torque shoulder of the barrel so it would align with the receiver properly when tightened. In other words the front sight had to be perfectly vertical and the extractor notch had to align with the extractor. That's what the lathe was used for.

The barrel in front of the sight was placed in the chuck.


The breech end needs to be secured and steadied during turning. One way to do this was to just run the live center into the chamber. Russ had a more innovative method which also protected the chamber from possible damage from the live center. He previously chucked and center bored a .308 dummy round to insert into the chamber and the dummy round would accept the live center. Take a look at the prepped dummy round.


Here is the breech. You will see the dummy round inserted into the chamber that the live center will go into and help steady the barrel while turning.


When the tool is cutting it is much easier to see what it is doing if you color the metal area being worked on with a stain called Dykem. It's a liquid that just brushes on with a self applicator.




Cutting the torque shoulder. Go easy and only take a little off at a time and check your progress by screwing the receiver on.


A posed shot showing the relationship of the cutting tool to the torque shoulder.


Here is the tail stock and tool assembly in cutting position.


Check your work frequently. Russ (left) with micrometer. He's mic'ing the barrel flats so he can modify a 1-1/16" open end wrench to fit on and tighten the barrel. Me (right) with the receiver to check barrel timing.


This dark picture shows the barrel timing to be at 11:00 o'clock, exactly where it should be after the lathe work, but before tightening the barrel.


Build to be continued.

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