fied with buying a new gun on occasion

Transcription

Visit SAR on line at: www.smallarmsreview.com
Firearms ownership has an amazing potential for personal growth. Some people are satisfied with buying a new gun on occasion and only shoot once in a while. Some people shoot a
large amount of ammo to become proficient and take up hunting or competitive shooting to test
and build their abilities. Some make the next step to loading their own ammo, either for enjoyment, cost savings or improved accuracy. The pinnacle for many serious firearms enthusiasts
is when you can actually build your own custom gun. With modular systems like the AR-15,
M16, M4 family it is easy to do, with numerous parts built to similar specs for simple assembly
into different configurations. Other guns are not quite as easy to build and start with pieces of
metal, commonly called receiver tubes or flats. They are not even finished to the point of being
considered a firearm and usually require an extensive amount of bending, cutting, welding and
drilling. Some of the more common home builds include MAC family firearms from flats, Sten
family guns from pieces of tube, and AK47 family firearms from flats. Although a little beyond
the ability of many weekend recreational shooters, they are not uncommon to see and several
templates, bending jigs and drilling fixtures are available to help the advanced builder. In this
issue we are going to go a step beyond the more common home builds and manufacture a firearm a little more complicated and extremely desirable. How about actually building your own
MP5 clone from a non-gun receiver flat? Thanks to LSC Manufacturing, LLC. it’s a project
much closer to the abilities of an advanced builder than ever before.
Below: This is what we started with for a demilled parts kit. It was an MP5A2 missing the center piece of the receiver.
It had a SureFire lighted forend, which is not uncommon on former police guns.
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Vol. 14, No. 8
Please Enjoy Our Bi-Annual Expanded Knob Creek Issue of Small Arms Review Magazine!
The Legal Stuff
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In the Beginning...
Vol. 14, No. 8
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pany with old-fashioned values, an eye
for detail and they pride themselves on
their customer service. Throughout this
build project we needed to contact LSC
several times to coordinate shipments
and update progress. They were always
available and happy to assist us at every
turn. Their goal is to bring back OEM
and from the experience we have gained
thus far, they are well on their way. LSC
Manufacturing has several new products
in many different phases and we will be
watching for their introductions as they
are announced.
Much to the delight of the “build it
Manufacturing debuted their BATFE apSAR
Show West, on December 5, 2008. These
design where many of the critical and
on a special jig and bent in a shop press, it
can be welded to form the general receiver section. There is plenty of work to do
even after this has been bent and welded
but it starts to take shape fast, in a way
that was once reserved only for those far
beyond the “hobby builder” category.
A major feature that sets the LSC Flat
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and spine, as well as all surface areas surrounding the bolt carrier once properly
folded and welded.
There are several steps involved to
Top: With an air driven cut off
wheel, we cut off the rear sight base.
You must use a gentle touch to only
cut the welds and not to damage the
sight base if you intend on reusing it.
Patience is an important commodity
in this phase of disassembly.
Center: After welds are cut from
the rear sight base, the whole assembly can be removed by using a
hacksaw to remove the entire unit.
Bottom: A bench grinder can be
used to remove the remainder of
the welds much easier once it is removed from the old receiver piece.
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Vol. 14, No. 8
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Out with the Old
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Top: After gentle grinding, the remaining portion of the demilled receiver can be completely removed
from the sight base using vice grips
and a vice.
Center: After removing all old welds
and receiver portions, the sight base
can be reshaped, cleaned up and
beveled as necessary for use on the
new receiver.
Bottom: Spot welds holding the barreled trunnion to the demilled receiver piece can be removed with a
gentle touch and the assistance of a
Dremel tool and stones.
Vol. 14, No. 8
33
be in as good a condition as possible.
First, remove every part that will be
needed for the new gun that only requires
a simple detail disassembly. This would
include all stocks and stock pins, bolt
and carrier, cocking lever and pusher,
bayonet lug cover, front and rear sights,
trigger group and housing, selector, magazine release, etc. Clean, degrease and
clean all these parts and put them in a big
zip-loc bag or box and label them for the
new build.
The parts you can reuse from the receiver pieces you have left are the barreled trunnion, the cocking tube, and the
rear sight base. These can be removed
with a Dremel tool or with air tools by
cleanly removing the factory welds. Extreme patience and caution should be
used when removing them so you do not
remove material from the parts you wish
to reuse. Refer to the photos accompanying this article to see how we removed
them.
An important note when prepping parts
for the build involves the fully automatwith your parts kit, and if you are or are
not going to need it. Once you bend and
weld the receiver, being in possession of
constructive possession problems. If you
used in the semiautomatic build we will
address it later in this article.
inal parts kit, when you are disassembling
your demilled parts kit it is an ideal time
to check the condition of all the parts.
Top: If spot-welds holding the demilled receiver section to the barreled trunnion prove too tough for
a regular Dremel, a cut-off wheel or
air grinder can be used with a very
gentle touch to remove the weld. Use
caution not to remove material from
the trunnion.
Center: When spot welds are almost
completely gone you can use a pair
of vice grips to remove the remaining
pieces of the old receiver piece. Notice the barrel is secured in the bench
vice with a set of aluminum barrel
blocks.
Bottom: A remaining spot weld can
gently be removed with an air sander
or grinder.
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Vol. 14, No. 8
Top: Remove the weld around the
circumference of the cocking tube
extension where it is attached to the
demilled receiver part just in front
of and above the trunnion and the
spot-weld on top. Be cautious not
to cut through the receiver section
as the tube slides back into the receiver a short way.
Center: After removing the weld
you can peel the old receiver section
away with vice grips and remove
any residual weld.
Right:
move any additional weld and to
square up edges again for reinstallation into new receiver.
Look for anything that may have been
cracked, broken or worn out. These parts
can be changed out at the time of the new
build and lessen the chance of having an
unsafe condition with your new build.
It can also lessen troubleshooting headaches if the new build is completed but
does not perform to your expectations.
It is also a good time to check the
headspace of the working relationship
between the original bolt, locking piece,
rollers and trunnion. The head-spacing
can be checked with standard feeler
gauges. Since you are going to be using
and installing the same parts, and the optimal positioning for these parts will be in
the same position with the same relationship once welded in your new receiver,
you are done. To check the head-spacing
with the demilled parts kit, with the bolt
locked fully closed into the trunnion,
you want to measure the space between
the bolt and the bolt carrier. It is easy to
check this relationship with a huge chunk
of receiver missing or even peeled back
from the old demilled receiver. When
it is reassembled in your new receiver it
is also easy to see this parts relationship
from inside the mag-well, looking down
from the top. With the bolt and carrier
locked fully into battery inside the trunnion, the “gap” between the rear of the
bolt and the front of the carrier should
ideally be between .25mm (.010 inch)
and .45mm (.018 inch). If it is outside
those parameters it can be adjusted by replacing the rollers with either oversized
or undersized rollers. Standard rollers
are 8.0mm and can be purchased from
Vol. 14, No. 8
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7.92mm to 8.04mm with an adjustment
range of +.04mm to -.08mm so you have
a fairly wide spectrum to choose from to
obtain the proper headspace.
At the time of your build you will need
a semiautomatic FCG to use with your
install it in the semiautomatic build, nor
welded into the receiver. If you do not
have a semiautomatic FCG you can modify a factory fully automatic FCG with a
few more steps. We already had several
semiautomatic FCGs to use from past
projects so we didn’t get into the modiavailable from LSC on their website. If
automatic FCG it is best to just discard
the one that came with the demilled kit.
Any Title II manufacturer will be happy
to take it off your hands or someone with
a registered “push-pin” machine gun may
be able to use it.
Even if you have a semiautomatic FCG
you may wish to use a factory fully automatic grip frame for aesthetics. It is not
a violation to have a grip frame marked
with the fully automatic (or burst) position and will look much more like a factory MP5 if that is the look you are after.
To use the frame supplied with your parts
kit, or any other factory fully automatic
Above
factory grip frames are attached with a
pushpin and the semiautomatic version
uses a shelf with no hole for attachment,
it will not simply slip on.
The shelf used on the semiautomatic
is wider than the space available between
the pushpin ears. To put it plainly, it
solve this issue is to simply cut the ears
for use with the original pushpins right
off. You can use a Dremel or even use
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have the option to measure the width of
the new shelf and remove some material
the direction we chose. If you want an
even more realistic look and not have two
empty holes in the ears you can cut off
the ends of the original push-pin and glue
one on each side giving the look of the
pin being inserted.
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Vol. 14, No. 8
The next change you will need to make
to the original grip frame is to remove
some material so it will slide over the
new shelf and hold the frame and trigger
pack in place. The original packs have a
steel plate in the front that will not allow
it to be used on a gun with a shelf. You
will need to open the slot in this plate to
allow it to slide over the new shelf. Since
there are several builders of semiautomatic versions of these guns and have
been making and converting them for
many years, we have seen a few different methods relating to the attachment of
the grip frame and the proper indexing of
the trigger pack. We will leave the style
you want to use to your discretion. Some
manufacturers will modify the trigger
pack so it actually sits on the new shelf
inside the grip frame. This is done by
removing a little extra material from the
front of the grip frame, allowing the shelf
to ride tightly under the trigger pack. In
this case the critical dimension is the
height of the cut on the trigger pack, as
it will relate directly to the height of the
shelf. The other method we often see is
where the grip frame is cut to a precise
height to rest directly on the shelf and a
little extra material can be taken off the
trigger pack since it never contacts the
shelf directly. For this build we cut them
both as even as possible to rest tightly on
In With the New
ceiver. Small Arms Research uses a 3-axis CNC Engraver and it is much easier to
with multiple contours such as an MP5.
Regardless of the marking method you
Center
Vol. 14, No. 8
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Top: As pressure is increased, the
receiver slowly rolls up and starts to
take shape. It is best to apply pressure very slow and continuously
monitor to make sure both sides are
bending up evenly.
Center:
ing should be very slow and keep adton (pusher) relating to the spacing
both ends are bending up evenly.
Bottom
bent up and all edges are checked
ing process.
choose, this is the best time to mark the
receiver with the least amount of trouble.
you will receive the “weld up kit.” It will
provide you with a new rear sight base,
which will save some prep time and the
shelf for the semiautomatic trigger pack.
You will also need the scope mounting
ing.
In order to effectively bend your restrongly recommend contacting Flat Solutions to purchase their bending jig. It is
a simple and effective mechanism and we
used it with ease. Those of you who are
a little more adventurous than this writer
may be able to fashion a jig yourself but
since one was available we didn’t tempt
fate any more than we needed to.
“ear” at each end to drop over a guide rod
and help it to stay centered while bending.
A steel ramrod dowel also slides over
these alignment pins after the receiver
will be pushing directly on the receiver
Two ram legs are inserted into the ramrod and the main ram is inserted over the
legs. The shop press pushes directly on
this main ram and this ensures that pressure is exerted equally. As soon as you
start putting pressure on it the receiver
is curling up much faster than the other
the jig can be repositioned in the press to
distribute the pressure equally.
Pressure is slowly increased until the
receiver sides are bent up and touching.
If they are not lining up even it is easy
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Vol. 14, No. 8
Above: The receiver is slowly TIG welded along the entire seam while checking for trueness on several occasions.
to tweak it by gently “rolling” it in the
press a tiny bit to help increase the lift on
the slow side. When they are all touching
and lined up, the front push rod will be
inside the newly formed magazine-well
and the rear will be inside the rear of the
receiver in front of the rear stock attachment point where you will later weld in
the takedown pin.
At this point we removed the receiver
from the jig and clamped it together. We
checked to make certain everything was
true by sliding the bolt carrier through it,
making sure it slid freely without hanging up on anything. At this time you can
snipping the guide ear at the rear. The
front guide ear may also be snipped off
surface on both ends.
After clamping and testing the shape of
the receiver we slowly started the weldand attach it at all points. Several times
during this process we stopped to recheck
moved freely. We had no problem with
it at this point so everything was smooth
but if you do have any issues where it is
snug, the easiest time to tweak the receiver is before it is fully bent and welded
Center, right: The shelf for attachment of the semiautomatic trigger
nal welding.
Right: Holes are drilled to create welding points to install the trunnion.
Vol. 14, No. 8
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Top: The trunnion and cocking tube
are installed in preparation for welding.
Center: To ensure that everything
was lined up perfectly, we manufactured a steel plug to slide inside
the front sight (in the bayonet “lug”)
and inside the cocking tube. This
would make sure the tube was centered perfectly before welding the
barreled trunnion in place.
Bottom: The trunnion and cocking
tube are welded to the new receiver
after being aligned.
for obvious reasons. To this point, if we
could recommend anything to Flat Solutions to make the build easier it would be
the addition of a mandrel that mimics the
shape of the bolt carrier, but much longer
and heavier. This would allow the manufacturer a tool to use for checking the inside diameter without the extra wear and
tear on the original bolt carrier. If it were
heavy enough it would also serve to assist in tweaking the receiver in the early
stages of the build, and possibly even help
small alignment issue arise.
After welding the receiver we needed
to add the shelf to hold the new FCG.
The placement of the shelf requires a
precise measurement where it covers the
area that the hole for the original pushpin would be on an original submachine
gun. After giving it some deep thought
pack inside and held it up to the receiver
using the rear stock takedown pin hole
for alignment. We marked the proper
location for the shelf and proceeded to
make a small tack weld after squaring it
up. At this point we slid the grip frame
and trigger pack over the shelf and slid
the stock over it to make sure everything
it in place. This method proved to work
The next step was to weld in the case
up kit. It is placed inside the receiver
While it may be welded in at an earlier
time in the build we chose to do it at this
time. Two small plug weld holes were
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Vol. 14, No. 8
tor in place and it was permanently attached. At this point we checked the in-
ceiver.
weld holes in the receiver to weld in the
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the point it is inserted into its position
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Top: The rear stock bushing is secured to be welded in place.
Center: The rear sight base is centered and clamped for welding to
the receiver after snipping the jig
alignment tab from the rear of the
receiver.
Bottom: After welding the rear sight
centered and prepared for welding.
Vol. 14, No. 8
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Left: The mag-well must be opened
triple-checking everything again, the gun
was cleaned of any debris and lightly lubricated. The remaining parts were installed and the furniture and sights were
mounted. Everything cycled well and
felt great but it was time for the true test
ing at the Small Arms Research Test Facility we loaded several magazines with
numerous types of ammo and hung a test
it is important to remember to insert the
cocking handle and linkage before dropping the bolt and carrier into the receiver
in case the roller lock mechanism on the
bolt drops into the trunnion.
After ensuring proper alignment once
again, the rear stock bushing was centered and welded into place, followed
scope-mounting piece.
This would conclude the welding. The
last step would be opening up the section
of the receiver to accept the magazine
release and installing the components.
ensure we had the proper placement of
the mag-catch we brought several plastic
“snap caps” to cycle through the feeding mechanism so we would know the
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magazine locked in at precisely the right
height in relation to the bolt. Most people reading this magazine are aware of
the headaches that can be caused when a
at the right height. If the magazine is too
high it can drag on the bolt creating cycling and feeding problems. If the magazine locks in too low it can have serious
feeding problems. Both issues can create a situation where factory magazines
must be altered to work properly and that
is frustrating and time consuming to deal
with. After several light cuts with a small
loading a single round into a magazine.
With great anticipation the trigger was
squeezed and: BANG!
The gun was examined, the brass casing was collected and evaluated, and the
target was inspected. The casing looked
This was repeated for several rounds with
the same results when we started loading
two rounds in the magazine. Most guns
ous problems, and even though we were
delighted it was feeding the single round
rectly, the real test would come in repeat-
Off to the Range
After picking up the workshop and
Vol. 14, No. 8
do.
The magazines, each with two rounds,
Above
were lined up on the bench and we in-
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What’s Next?
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Vol. 14, No. 8
43
set, it was decided
ing process as well.
It wasn’t a “normal”
MP5 so a normal
do.
After
doing
a
in Florida (Hydro
Print Services) specializing in Hydro-
The feed, function and accuracy
of the “home rolled” MP5-SBR has
been second to no other MP5 variant
the author has ever owned, including
original German factory guns. This
also known loosely
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30-round magazine of Federal 147-gr
ammo, off-hand, at 25 yards with the
AWC suppressor. The gun has yet to
sembly.
becoming available
to single piece end
reserved for only
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Observations and Conclusions
silencer, etc.) is cleaned and prepped and
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patterns, I decided to let my 7-year old
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done.
tion.
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able pricing.
44
in over and over. It’s far from a longVol. 14, No. 8
family weapon the easier it will be. The
learning curve drops fast when the parts
relationship is already known. It may
take someone who does not have much
time on the MP5 platform a little longer.
trol group we already had available, you
can plan on spending a few more hours in
converting the factory FCG for semiautomatic use if you choose that direction.
Also, since this writer is an 07/SOT we
didn’t have any wait time for approval in
the SBR build, nor did we have to permanently pin a barrel extension to achieve
the 16+-inch barrel length necessary to
The end result is certainly something
to be excited about. This single build has
shown us that properly built, it functions
on par with any of the numerous factory German guns this writer has had the
pleasure to own and it is incredibly accuit, some with a great amount of time on
mented on its accuracy and are surprised
from LSC worked great and nothing was
misrepresented at any level. Their staff
was helpful in all questions. At a retail
up kit we believe there will be several additional “to do” lists for our fellow RKIs
in the coming months.
Sources
MP5 Flats & Parts Kits
LSC Manufacturing, LLC.
P.O. Box 521
Ph: (310) 699-9150
Email: [email protected]
www.LSCManufacturing.com
Parts and Parts Kits
www.HKSpecialist.net
www.Subguns.com
www.Sturmgewehr.com
Flat Bending Jig
Flat Solutions
[email protected]
Hydro Print Finishes
Hydro Print Services
5400 Park Blvd.
Pinellas Park, FL 33781
Ph: (727) 544-7935
www.HydroPrintServices.com
Vol. 14, No. 8
45

fied with buying a new gun on occasion

Transcription

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