How
to Build an AK-47
Part Two of our series on US AK47 builders
- Matt's home shop AK47 building method
Update
3/02/06
From: http://rtccom.net/~mattb/ak_build.html
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OK..........it's done.....and
fired! I planned on updating before now, but again,
I felt more like working on the AK than working on
the page, heh. Then I was lazy and decided maybe I'd
just wait til the test firing. So here we are....but
first, let's pick up where we left off.
The process
As promised, here's a pic showing
how I transferred the hole pattern from the trunion
to the receiver:
The process |
I placed this piece of
paper over the fron trunion, being careful to
align its front and top edges with the front
and top edges of the trunion. Then I punched
holes in the paper over the trunion holes. I
then placed the paper on the receiver, again
aligning the front and top edges (as seen in
this pic), and ran the pencil lightly around
in the holes. It didn't work out perfectly but
for most of the holes it was pretty close (2
or 3 were almost PERFECT). The important thing
is both trunions are very secure, no play at
all. The gun is solid.
|
Here's what you end up with:
Drilling guides |
The receiver, with trunions installed |
After drilling out the receiver,
I fit and sanded the buttstock and lower handguard.
Took a lot of sanding on the buttstock, lower handguard
didn't need much.
Getting there.......
I also hit the edges
of the top rails (top of receiver) with the Dremel,
then polished them. This was all that was needed to
eliminate the binding of the bolt carrier around the
middle of the receiver. At this point I was thinking
things would be pretty easy...........just got to
assemble the fire control group. Well, as simple and
user-friendly as the AK design is, installing the
hammer and trigger is rather troublesome. You have
to keep pressure on the hammer against its spring
to keep the hammer lined up with the holes in the
receiver. Then the hammer has to be installed, with
its rearward hooks placed UNDER the hammer spring
(installing the trigger first doesn't seem very practical,
because with it in there's not really enough room
to get the hammer installed....you can't just drop
it in, because of the rails). Simple and effective
design, but a bit troublesome to install (seems to
me, anyway). Then the axis pins for the hammer and
trigger have to be retained somehow. I never could
get the retaining wire from this kit or the wire from
another kit to work, I ended up using the small clips
that came with my screw/bit/tap/parts package. Still
a little finnicky to work with, but not too bad.
But then another problem presented itself..........the
bolt would NOT cycle. It binded a lot near the limit
of its rearward travel, and when coming back, it got
hung up at the hammer. I couldn't even force it past
the hammer, at least not with any reasonable effort.
After consulting with the good folks at sksboards.com,
I got the Dremel out again (what would I do without
that thing? LOL!) and ground the face of the hammer
where it contacts the bottom of the bolt carrier.
After lots of grinding and polishing, the bolt carrier
was able to pass over it without much resistance.
Pic:
This pic shows approximately where I had to grind
the hammer
There's still a fair amount of resistance between
the bolt carrier and hammer, but that's ok.....as
long as the bolt carrier cycles, it's fine. You don't
want to take TOO much off, as the bolt carrier has
to push the hammer down far enough for the hammer
to slip under the trigger hook(s).
The binding near the rearward extent of the carrier's
travel turned out to be the safety lever........the
shaft of the lever, inside the receiver, is U-shaped,
the bolt carrier is supposed to pass through this
U-shaped area. It wasn't quite clearing, so I had
to grind it down some. OK, bolt seems to cycle ok
now.............ooops, now it's hanging when brought
all the way back...........
The bolt carrier/bolt assembly is installed by lowering
it through the top of the receiver near the rear trunion.
The top edges of the receiver are narrower here, so
there's enough space for the assembly to drop in between
the top edges of the receiver. It seems this area
was just a bit too wide on my receiver, and/or started
too far forward. The only way around this that I can
see is to restrict the bolt carrier's movement so
that once installed, it doesn't go all the way back.
Some more research indicated this actually is a problem
on some AK's. The typical fix is to install a recoil
buffer. This is a piece of plastic that goes in front
of the rear trunion, to avoid the violent metal-to-metal
contact you get when the bolt carrier comes flying
back after a shot. Of course it also keeps the bolt
carrier from coming all the way back, which is what
is needed to fix the popping-out-of-the-rails problem.
I got a 1/4" buffer from Black Jack Buffers,
which fixed the problem.
|
Check out the following pic. The area in the
red circle is the part of the safety selector
shaft that I had to grind down. The areas in
blue are the corners of the top edges of the
receiver, where they start to narrow for the
bolt carrier drop-in area that I suspect are
a bit too far forward. |
Receiver fitting |
FINALLY, everything
was ready.
The Big Day!
It was WINDY, but the temperature
wasn't too bad, and there were just enough clouds
about to keep the glare down. Me and Matt P loaded
up our stuff and headed to the shooting area behind
his house. I had 3 magazines loaded, plus an empty
that I loaded with just 2 rounds once we got there
(just in case something went wrong, I didn't want
to have 29 live rounds sitting right under the chamber
of the rifle.......2 rounds would allow me to fire
the gun and verify that it cycled and fed properly).
I pulled back the
charging handle and let it go, first round chambered
ok. Pull trigger........BANG. Pull it again....BANG.
YESSSSSSS!!!!!!!!!!! SUCCESS!
Wow, I didn't expect
the huge, dramatic muzzle flash this thing spits out!
Check out this pic of Matt P firing the gun:
Fire-breathing AK
It's quite noticeable
even from the shooter's viewpoint. It's pretty awesome
firing this thing from the mid position (not quite
hip firing, but lower than the shoulder) traditionally
used for mass destruction and indiscriminate spraying
of lead, with all the noise and recoil and a huge
flame coming out of the muzzle on every round. :)
I'm not sure if it recoils worse than the SKS........they
weigh about the same I believe, so probably not, but
it just seems more violent. It also has a different,
louder report. Definitely a distinctive sound. :)
I had 159 rounds to
shoot off. Fortunately, Trent came out with his dad's
SKS and a couple of other guns, and brought some 7.62x39
with him. I think we ended up putting a little over
200 rounds through the AK, total. I had exactly ONE
failure with the gun.......the hammer didn't cock
once. And I'm not even sure it was a problem with
the gun....I was bump-firing and accidently let my
hand get in the way of the charging handle as it slammed
back during firing (yeah, ouch). I suspect this might
have kept the bolt carrier from coming back far enough
to cock the hammer. The trunion screws did loosen
a bit, which I expected since I didn't put any thread
locking compound on them yet. Unfortunately one of
the front trunion holes stripped out, I guess it had
backed out a lot before I noticed it and thus was
under a lot of stress. I don't think I can get by
with slopping a bunch of thread locking compound on
it, I'll probably have to re-drill and tap it for
a larger screw. :( But it's one of the rearmost screws,
so it shouldn't be too much trouble to fix.
I also noticed the
screws holding the trigger guard in place backed out
a bit, and a couple of them stripped out (I was afraid
of that, with the shallow threads due to the holes
being slightly oversized). So I guess I will go with
my original idea of installing metal plates on either
side of the trigger guard inside the receiver. The
plates will be drilled and tapped for the trigger
guard screws.
Oh yeah, this thing
bump-fires awesome. I haven't polished the trigger
or hammer yet so I didn't think it would bump all
that well, but the trigger seems to break sooner than
the SKS's trigger, which apparently helps quite a
bit. :)
More pics from the
session:
Our little arsenal
And finally, a "glamor
shot" of the AK in its completed form. :)
Ahhhhh awesome
Next things to do..........disassemble
the gun and check everything out real good (and clean
it, heh), fix the stripped out trunion hole, put some
thread locking compound on the trunion screws, polish
the trigger hooks and the hammer, and fabricate some
plates to place inside the receiver to thread the
trigger guard screws into.
Yeah, this gun rocks.
:)
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