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Gun&Ammo Combat Arms 1997
M14A2 Article
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| At 200 yards with surplus military 7.62mm NATO ammunition, the author's
"instant custom" M14 easily placed all shots in the chest and head region of
this target . The center group was 2.15 inches in diameter |
M14 receivers are shown at five
stages during CNC production. Top to bottom: 1) 12 1/2-pound block of 8620 steel; 2)
roughed to shape; 3) first surface contour cut; 4)interior cuts; and 5)
finished receiver
with a coat of black oxide. |
The factor that attracted me to the original M14 rifle besides the
connection with the U.S. military was the fine machine work and precision with which the
rifle was built. The receivers were cut from bar stock into bars weighing nearly 12
pounds. Skilled machinists then painstakingly "carved" the intricate receiver
from the steel, working like latter-day Michelangelos with machine tools instead of
hammers and chisels. The M14 was the last military firearm to be so manufactured, and it
is one of the finest military semi-automatic rifles ever built.
THE M14A2
I have owned and still own a variety of M14-type rifles. As good as
many of them are, their receivers were castings and did not duplicate either the type of
steel used or the fine machine work of the originals with only one exception. Entréprise
Arms of Irwindale, California, recently duplicated the original M14 receiver from steel
bar stock using computer-controlled machinery. They have produced a receiver as fine as
anything that came out of the Springfield National Armory, and have named it the M14A2.
Entréprise also manufactures fine machined receivers for the L1A1 and
Israeli FAL rifles. Using the most modern Computer Aided Drawing (CAD) programs and
Computer Numerical Controlled (CNC) machine tools, they produced these excellent FAL
receivers from solid blocks of steel. The same team has now applied its expertise
successfully to the complicated M14 receiver, showing that it has done its history as well
as manufacturing homework. Entréprise has designated its receiver the M14A2. As you
probably know, production of the M14 and the M14A1 was ended in 1964 by then Secretary of
Defense Robert McNamara in favor of the M16 rifle.
CNC QUALITY MACHINING
The Entréprise M14A2 receiver is manufactured from solid 8620 steel
bars, as were the original M14 receivers. The machining process that reduces the solid
chunk of steel to a finished receiver is controlled by computers, so tolerances can be
held to .0001 inch where necessary.
Recently I watched the entire process. Solid blocks of 8620 steel
weighing 12 1/2 pounds were secured in a jig in a CNC milling machine. Five separate
operations that automatically roughed the receiver to shape were performed on each steel
block. The rough receiver was then transferred to the next CNC milling machine, which
performed six more milling operations. The final five milling and drilling operations were
performed in a third CNC machine that produced a receiver ready for final polishing,
hardening and finishing. The process took minutes rather than hours, and the end result
was a finished receiver that matches the original M14 specifications established by the
U.S. Army Ordnance Department at Springfield National Armory in 1957.
After the machining operations, the receiver was sent to quality
control for gauging and measuring. Entréprise uses the same quality-control
specifications that were applied to the M14 receivers made at the National Armory and by
Harrington and Richardson, Winchester and TRW when the original M14 was being built in the
1960s.
All Entréprise M14A2 receivers are exterior hardened to 55-57 Rockwell
C to a depth of 1/20,000 of an inch, as were the original receivers. The receivers are
finished in a mil-spec Parkerizing, but are also available in a black-oxide finish from
custom gunsmiths who intend to build custom match rifles and want to refinish the
receivers to their own specs
BUILDING AN M14A2 RIFLE
But manufacturing a fine receiver is only one factor in building an
M14-type rifle. How well do M14 parts kits (available from various sources) fit? Will the
fee charged rise astronomically because parts have to be fitted, holes redrilled for pins,
screw holes redrilled and tapped for bolts or metal cut away to mate parts into the
receiver in their proper orientation? And will the assembled rifle then be legal under the
often confusing and contradictory federal laws?
We asked John Capalbo, the very capable gunsmith for Heritage Gun Room
of Santa Ana, California, to assemble a service-grade M14A2 rifle for us. Entréprise Arms
furnished a new M14A2 receiver, and the Dealer's Warehouse of West Sacramento, California
provided us with an M14 parts kits that contained everything but the original receiver.
John has built numerous service- and match-grade M14-type rifles previously for clients.
The M14 parts were manufactured originally by Winchester in May of
1961. The rifle from which the parts were taken had seen service, but the rifling in the
bore was sharp and clean, indicating it had not been abused.
John began by laying out all the parts and inspecting them for flaws or
damage. He then cleaned them all thoroughly. The most important aspect of building any
rifle is mating the barrel and receiver. Any gunsmith will tell you that this is where
most problems occur, particularly with semi-automatic rifles. For starters, the barrel
threads must match the threads cut in the receiver. Next, the barrel must index properly
that is, it must screw into the receiver the correct distance to allow the front sight to
be vertical in relation to the centerline of the receiver and the rear sight. In addition,
the chamber in the breech end of the barrel must be positioned properly so that the
cartridge headspaces correctly.
John clamped the barrel securely in a hydraulic press. He marked the
centerline of the receiver for an index mark, and then turned the receiver onto the barrel
threads. Using a wrench, he carefully torqued the receiver over until the index mark on
the receiver lined up with the index mark on the barrel. The rear sight was assembled onto
the receiver, and the alignment with the front sight was checked using a centering guide.
The rest of the assembly went quickly The bolt release provided in the
kit gave a bit of a problem due to a bent pin; however, John replaced it with a new roll
pin. The bolt was lubricated lightly and slid into the bolt rails. It went forward, and
its lugs locked home in the receiver wall when the receiver was tipped down. The operating
rod assembly went on next, and then the stock.
I had chosen a fiberglass stock manufactured by TRW for the M14A2
rifle. Fiberglass stocks were scheduled to replace the wooden stocks on the M14 rifles,
but the rifle was withdrawn from service before the changeover could be completed. The
non-porous fiberglass stock eliminated many of the "wandering point-of-aim"
problems encountered with the original M14 wooden stock as it absorbed and lost moisture.
The trigger assembly slid into place without problem and latched down
with some effort, assuring a tight fit in the stock. A headspace check showed that the
chamber was well within the limits specified by the U.S. Ordnance Department: 1.6355 to
1.6385 inches. The total time it took to assemble the completed rifle was less than 25
minutes.
We now knew the Entréprise Arms M14A2 receiver was properly
constructed for easy assembly But would it shoot properly? Three days later, at a range in
the San Gabriel Mountains of Southern California, we fired 50 rounds rapid-fire with the
rifle locked in a rest. The 7.62x51mm ammunition used was military surplus manufactured by
Fabrique Nationale to NATO specifications and dated 1967. There were no malfunctions of
any kind. Fired cartridge cases showed no signs of undue pressure backed-out primers,
bulging heads or malformed shoulders. Fired cases averaged 2.007 inches in length, another
indication that the chamber and headspace tolerances were well within specifications.
We next fired the rifle for accuracy. With the rear sight dialed eight
clicks up for 100 yards, we fired a three-shot group that averaged 1.4 inches. Adding four
more clicks of elevation, we next shot hanging metal plates 14 inches in diameter, and we
struck repeatedly at 200 yards. As the afternoon waned, we set up a silhouette target at
200 yards and, shooting from a bench-rest, fired five three-shot groups that averaged 2.3
inches in diameter.
We were more than satisfied with the accuracy that we were able to
achieve from a standard service- configuration rifle assembled from a "kit" of
used parts. Our next project will be to build an M14A2 match rifle using a new cut-rifling
barrel and a custom stock. Judging from the results described above, we should have no
trouble achieving one-half-minute-of-angle accuracy.
The new Entréprise Arms M14A2 receiver holds great promise for those
who desire a fine M14-type match rifle. The M14A2 receiver appears amenable to the
attentions of custom gunsmiths who specialize in building fine match-grade M14-type
rifles. Although we were working with a prototype M14A2 receiver, production had already
begun as this article was being written. By the time you read it, the M14A2 receiver will
be available from your favorite dealer or custom gunsmith.
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| The
receiver on the left, machined from solid 8620 bars of steel, shows thicker walls and more
defined contours than the cast receiver on the right |
Gunsmith John
Capalbo
assembles the rear sight to the m14A2 receiver and replaces a bent magazine release pin in
the m14 parts kit with new roll pin. |
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