The lower receiver was relatively simple to accomplish. The upper should be fairly simple also,
however it's the most critical part of the entire build. It's not something one should
rush or do half assed because life and limb could be at stake if done improperly. Follow along
as I take my own sweet time building the upper receiver striving for perfection and paying
attention to details to hopefully produce a trouble free product.
Before I permanently attach the muzzle device and coat the barrel with Duplicolor, I wanted to
ensure the barrel hand timed to the receiver properly. As you can see in the top left pic, it did
not. It hand timed to about the 10 O'clock postion instead of the preferred 11 O'clock position.
Using a little trick I learned on The FAL Files Forums in a post I can't seem to find now, I went
about shaving a few thousands off the barrel shoulder to correct the problem (Top Right Pic). Using
a 36 grit sanding disk with the hole in the middle sized to just fit over the threads, I placed it
"grit side" towards the barrel's shoulder and screwed the barrel back onto the receiver to use as a
backing plate. Slowly but surely working the sanding disk around and around the barrel keeping pressure
on it by keeping the barrel tightend up to the disk, it reduced the barrel shoulder down to where it
should be. A leather glove was donned soon after the pic was taken to save wear and tear on my hands.
As you can see in the lower left pic, the sanding disk produced a very nice, clean and even cut with
no divots or wavyness. The pic at lower right shows that I succeeded in getting the barrel to hand
time to the 11 O'clock position. The best way to eyeball it, is to make a triangle out of the cutout
of the barrel shoulder and the gas tube boss of the upper receiver.
Next, I proceeded to permanently attach the muzzle device to the barrel. Using simple green and
denatured alcohol, I thoroughly cleaned the threads and about 3" of the barrel behind the threads.
I also doused the muzzle brake in simple green and denatured alcohol then blow dried it out with
compressed air. Satisfied that I'd cleaned the areas well enough to be silver soldered, I applied
a generous amount of "Fusion" silver solder paste (Top Right Inset) to the barrel threads (Bottom
Left Inset). Next, I threaded the muzzle device onto the barrel and indexed the ports to where I
had two rows up and two rows down and centered in relation to the front sight post (Bottom Center
Inset). I then took a "Mapp Gas" torch to heat an area where the threads are on the muzzle device
(Bottom Right Inset) until I saw it glow a dull red, then danced the flame around the circumference
of the muzzle device to distribute the now molten solder evenly around the threads. A Mapp Gas torch
is recommended, because a regular propane type torch doesn't get firearm grade steel hot enough to
melt the silver solder paste and enable it to flow into the metal parts properly. Lastly, I moved
the flame of the torch toward the back of the muzzle device to visually inspect whether or not the
silver solder had indeed flowed onto both the barrel and muzzle device, then left the barrel to
cool by air while I post this update. =)
Although not technically part of the upper receiver assembly, my "Para style" rear sight assembly
from Volunteer Ordnance Works
(VOW) came in today (July 15th). Come to think of it, it *is* the upper most item on the rifle
so.. =) Anyways, it was installed in place of the stock rear sight soon after arrival. No fitting
or fuss was encountered at all during the installation. This rear sight has a dual flip up/down
aperture system (Inset Pic) that was scavenged from the AR15A2 (M16A2). It also shares the same
windage adjustment knob which was optional. I personally think it'll be a definite improvement
over the range adjustable stock rear sight, since this is a carbine that will have a dot or reflex
type scope mounted to it eventually.
Applied Duplicolor 1200º paint to the barrel/muzzle device and a few other parts that were
left unfinished from the last "Bake-On Finish"
session. They came out looking rather spiffy! Yes, as you can see I remembered to coat
the rear sling swivel parts this time around. =)
I did some checking of parts fit on the upper. One area of concern, is extractor clearance cuts
in the upper receiver. Mine didn't need any alteration, but some of the Imbels do need a little
judicious relieving of an area just to the rear of the barrels breech. I used a dummy cartridge
(Top Pic) to check for clearance in this area. Also, there have been reports of issues with the
TAPCO 3rd Generation Scope Mount (Bottom Pic) interfering with the bolt carrier. I found that
if you place the bolt in it's rails of the upper and use it to align the scope cover as you
systematically tighten down the screws, that this is a non-issue. I could tell no hinderance to
the bolt carrier travel attaching the scope mount in this manner. I have hex socket cap screws
that will replace the standard slotted screws (displayed in pic) that came with the mount.
Set about torquing the barrel till it was properly timed to the upper receiver. Actually it was
anti-climatic to what I had expected. First, I placed the the upper receiver w/electrical tape
around the circumference where the receiver wrench would come in contact (to protect it from
aluminum smears) into the receiver wrench. I then placed the wrench and receiver in my Wilton
6" bench vise and cranked it down tight so it wouldn't budge for the next steps (Upper Pic).
Taking some anti-seize compound that can be had at any auto parts store, I dabbed some around
the barrel threads (Bottom Left Inset). Probably more than needed cause the stuff gets everywhere!!
I hand tightened the barrel to the receiver and it hit the same 11 o'clock mark as before (Bottom
Center Inset). Don't forget to put the handguard ring on the barrel before threading the barrel
on for the final time or you'll have to do this all over again or go without handguards (Not
recommended). Took a 1 1/16" Craftsmen combination wrench that had the box end lopped off
then smoothed, and the open end clearanced a bit to where it would just fit the barrel flats
with a little persausion of a hammer and drove it on (Bottom Right Inset).
Slid a 2ft section of galvanized 1 1/4" pipe over the end wrench (Left Pic) for leverage and
cranked that baby home!! It takes about 100 ft.lbs of torque to crank it home if hand timed
properly. If you have to shave your barrel shoulder, be sure and check your hand time with a
wrench to ensure you don't get a false reading. As you can see, (Right Pic) it timed perfectly.
Also note handguard ring =). I verified barrel time by eyeball, but some use the two rod method
to ensure it's properly timed. Place a 3/16" steel rod of about 2-3ft in length through the
handguard screw hole in the gasblock on the barrel and balance the second rod on the flat of
the upper receiver. Sight down the barrel from a distance at the muzzle end to see if there
is any mis-alignment. Either way, you're still relying on your eyesight to judge if it's
timed properly or not. One other thing I did before calling it timed, is thread the gas
tube and gas nut onto the gasblock and receiver to see if the gas piston would move
freely. It did!! =) Headspacing is next...
Shoot Safe!!!
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The lower receiver was relatively simple to accomplish. The upper should be fairly simple also, however it's the most critical part of the entire build. It's not something one should rush or do half assed because life and limb could be at stake if done improperly. Follow along as I take my own sweet time building the upper receiver striving for perfection and paying attention to details to hopefully produce a trouble free product.
