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The SIG AMT Rifle in America
Reprinted from Small Arms Review, June 1998
Written by William R. Bishop
article provides an overview of what is arguably the highest quality military-style rifle
to ever be imported into America - the SIG AMT By understanding the background, technical
details, operating characteristics and accessories of the SIG AMT you will gain a
perspective into why it is considered one of the finest rifles of its type in existence.
Have doubts about this grandiose statement? Then read on!
During the period
1954-1957 the Swiss firm of Schweizerische Industrie Gesellschaft (SIG) designed an
assault rifle which ultimately became the Sturmgewehr (StGw) 57. The StGw57 was in the
7.5mm Swiss caliber and borrowed ideas from the earlier Spanish CETME Model L and Mauser
StG45 rifles. Chief among theses ideas was using a receiver of stamped steel along with
delayed-blowback operating system comprised of a bolt assembly utilizing twin locking
rollers. These locking rollers are most commonly seen today in H&K rifles.
The Swiss military used the StGw57 from 1957-1986 at which time it was phased out in favor of the newer StGw90 in 5.6 GP90 caliber. However throughout the distinguished 30-year service life of the StGw57 several updates of the basic design took place. These were done to increase its suitability for export purposes onto the global arms market. The updated StGw57, when exported out of Switzerland, then became known as the StGw510. Options available within the 510 series included differing calibers, weight reductions, ergonomic refinements and simplified sighting equipment. There were five versions of the 510. These included:
510-1 Same as the StGw57 but
renamed for export purposes
period 1969-1989, SIG exported two versions of the 510 into the US. One was the 510-1
which was renamed for sales purposes as the PE57 and remained chambered in 7.5mm Swiss.
The other was the 510-4. The remainder of this article will touch on the 510-4 and then
detail its refined brother - the superb SIG American Match Target (AMT).
1969 several SIG 510-4's, perhaps less than a dozen, were imported into the US. These were
legally parallel to the FN "G" series rifle in that they were built around full
automatic receivers with semi automatic internals. However, BATF approved these rifles as
semi-automatics and therefore not falling under the restrictions of the NFA.
in 1969 SIG responded to emerging gun regulations in other countries (notably England and
Italy) by slightly modifying the 5 10-4 to make it more "sporting". This
included deleting the bayonet mount and rifle grenade rings on the barrel. When imported
into the United States this now became the SIG AMT. Benet Arms, SARCO. Osborne Brothers
(import marking of "OSS"), Mandall. SIGARMS and Golden State Arms all were AMT
importers. It is known that 1,440 AMT's were imported during the period 1969-1978. From
1979-1989 more AMT's were imported although they were reportedly made up of parts which
had been manufactured earlier. Total import of the AMT is estimated at 3,000 rifles for
the years 1969-89. Even SIG does not know the exact number.
The AMT is Superbly manufactured and finished in every respect. The traditional quality of Swiss workmanship is evident throughout all parts and functions of the rifle. After all, being directly related to the primary small arm of the Swiss military though the, it would have to be!
The AMT is not a big rifle, although it visually appears to be larger than it really is. Total length is 40" with an unloaded weight of 10 pounds. The charging handle is on the right side of the receiver and is extremely easy to grasp. The large ejection port is also on the right side and there is no ejector door as on the M16. The staggered row box magazine comes in 5, 10 and 20-round versions although the 24-round 7.5mm Swiss PE57 magazines will fit and function correctly if it is the older metal (not plastic) follower. The hollow black plastic pistol grip is quite comfortable to use and has a removable end cap to allow storing the cleaning kit.
From a side view the AMT appears to be a square and perhaps bulky rifle which could be uncomfortable to use. This is definitely not the case as it very readily falls into your shoulder when firing. The relationship between buttstock, forward hand rest and trigger assembly are excellent. Overall fit and finish are the best I have ever see in any production rifle, anywhere. Finally, the major components of the AMT are all numbered to each other in traditional European fashion.
Receiver - The receiver is
essentially composed of three pieces: two end caps which are blued, and parkerized central
receiver section. The central section is stamped steel with several ribs to give rigidity
and also perform a self-cleaning function. The front end cap is a
cast and precision machined component which is spot welded to the central section. One
unique feature of this cap is that the bolt locking roller recesses are contained in
separate parts and held in place by circle clips. When the recesses become worn simply pop off
the circle clips, install new locking recess parts. and replace the circle clips. Your AMT is now
ready for thousands of new rounds to he fired. The rear end cap is also spot w
the central section and lends structural support while serving as a mount for the
buttstock. Typical for the period, a carry handle is mounted into the receiver and is
placed where the AMT naturally balances.
- The blued steel barrel is 19.9" long and has four-groove rifling with a 1/
12" twist rate. This is an optimum geometry for 7.62mm NATO slugs in the 150-165
grain weight range. Accuracy with milspec ammunition is excellent as my AMT routinely
delivers 2 MOA with iron sights and my poor eyes. The barrel is threaded and torqued into
the upper receiver and is covered for 1/2 of its length by a perforated aluminum barrel
casing not only assists in preventing unwanted banging of the barrel during field use but
also acts as a heat sink and protection against hand burning. It is easily removable and
contains the front sight assembly, hand rest and folding bipod. The barrel is also
threaded for a flash suppressor which closely resembles the M 16 birdcage version.
System -The AMT fires from a closed bolt. In fact, the full automatic StGw57 and
510-series all fire from the closed bolt. Pulling back on the very large charging handle
(it is shaped like a miniature beer keg!) and letting it fly forward to load a round into
the chamber is a very satisfying experience as all bearing surfaces are finely machined.
It feels like glass sliding on glass. The charging handle has a detent which locks it
forward and therefore keeps it from cycling as the bolt reciprocates. Also, the chamber is
fluted to aid in initial extraction of a spent cartridge. While these flutes are not as
prominent as on the H&K, there are more of them.
AMT's delayed blowback system uses twin locking rollers. The bolt assembly is quite
similar to the H&K system in that a smaller bolt head contains the locking rollers and
extractor. The larger bolt body contains the firing pin and a protruding director shaft
(acts just like the H&K locking piece) which causes the locking rollers to cam into
their recesses at the moment of firing. After the bullet exits the bore and pressures drop
to a safe level the bolt body moves rearward and pulls back the director shaft. This
allows the locking rollers to release out of their recesses and the entire bolt assembly
to continue recoiling back. cock the hammer, and compress the recoil rod/spring
combination. Upon reaching the limit of travel the rod/spring drives the bolt assembly
forward to strip and chamber a fresh cartridge. As the bolt assembly comes back into
battery the locking rollers are then cammed back into their locking recesses by the
director shaft and you are ready to fire another round.
Sights - The front sight is a post which is protected by ears. Elevation adjustment is carried out by screwing the post the appropriate direction as on the AR 15. However. unlike the AR 15, traversing adjustment is performed by drifting the front sight base left or right. The rear sight is of the aperture type and is spring loaded to slide up or down a ramp which is ballistically matched to the 7.62mrn NATO round. This ramp is graduated - with detents from 100-600 meters. Sight radius is a generous 21 ".
All AMT's have wood furniture composed of a buttstock and two piece forward hand rest. The
wood is French walnut which is smoothly finished under a flat polyurethane coating. While
both appear to be too small, this is definitely not the case. The buttstock has a hollow
scooped from its midsection to allow an excellent cheek weld and proper alignment of
eyeto-sight. The forward hand rest falls readily in place and is shaped to permit a good
grip at a comfortable arm/body angle. Because of its straight-line design the force of
recoil is directed against the shoulder muscle and the AMT does not unduly rise even in
rapid fire. It is the softest recoiling 7.62mm I have ever fired. In
comparison the H&K91 and FN FAL are like elephant guns.
the AMT is a pure joy. The balance and excellent ergonomics are hard to appreciate until
you shoot several hundred rounds through it - at one session.
begin load up the magazine and insert it into the rifle. This is done in the same manner
as a FAL or H&K. Place the forward part of the magazine into the mag well and rock it
backwards until it latches in place. While keeping the AMT pointed downrange, grab the
very large charging handle and pull it smartly to the rear. Letting it go will immediately
place a round into the fluted chamber. At this point take it off Safe and start firing.
You can always tell if the AMT is loaded as a cartridge indicator is built into the upper
receiver. It will pop up a fraction of an inch if a round is chambered. In the darkness
you can reach forward and feel it protruding. There is also a secondary cartridge
indicator which is part of the firing pin lever and viewable/touchable through the
there is no hold open on the AMT the bolt will not lock to the rear after the last shot.
It will close on an empty magazine just like the H&K. A hint which can prevent some
minor marring is to not let the AMT "run dry"' on a magazine. They are hard to
find and expensive ($ 130 each) to purchase. As you come up on the last round it is better
to remove the magazine instead of having the bolt slam into the magazine follower. Make
sure you take care to manually eject the round which is still in the chamber!
shooting is perhaps my favorite position with the SIG as it really brings out the rifle's
inherent solid design. However, the factory manual states the preferred position is with
the built-in bipod as it yields the greatest accuracy. While not disagreeing with this
statement, it does sort of take the fun out of standing up and enjoying an extremely well
built firearm with minimal recoil.
the AMT is quite simple. First, make it safe by taking out the magazine and charging it.
Place the selector lever on "S" and push out the single pin which retains the
lower receiver. Swing down and remove the entire lower receiver. Depress the buttstock
latch, rotate the buttstock 90 degrees counterclockwise and remove it. The recoil spring
and rod will come out with the buttstock. Grasp the charging handle and slide it to the
rear. The bolt assembly and charging handle can now be withdrawn from the receiver.
Finally, split the bolt assembly by removing the transverse key. That is all there is for
general disassembly. Detail stripping is not necessary except for once or twice a year.
Standard cleaning procedures should be used but make sure no aggressive chemicals such as carb cleaner, Tetra Teflon solution, Gun Scrubber, etc. come into contact with the wood furniture. The fine finish on the wood may not be able to take these aggressive compounds. Also keep in mind the fluted chamber harbors additional crud and should be addressed a little more thoroughly. A US GI 7.62mrn chamber brush will work quite fine. As the upper receiver is now wide open you can properly clean the bore from the breech side.
AMT has available several accessories which add to the enjoyment of owning this fine
weapon. In addition to the 5, 10 and 20-round magazines there is also a cleaning kit,
cartridge indicator hold open tool. locked breech gauge (similar to headspace) and sight
adjusting tool. Since the AMT is still being sold in Switzerland the availability of most
spare parts is assured. One location to get these parts is through SIG Parts Service of
Auburn, WA, or you can file the necessary Form 6 with BATF and import them yourself.
the hardest accessory to find is the very rare scope and QD mount combination. Reportedly
there were about 100 scopes made in the 1970's by the firm of Dr. Wohler from Kassel.
Germany. Half of these went to the Chilean army for their use and the remainder were
placed on the retail market. The scope is 4x with a 1" tube and comes with the
traditional picketpost reticle pattern. It has a range adjusting knob which is cammed for
the standard 7.62 NATO ball round.
quick disconnect mount is equally hard to find. Fortunately, SIG Parts Service does a
first class job of reproducing this mount which is currently available for $325 If you
want to put optics on your AMT this high quality mount is clearly the way to go. Since the
Dr. Wohler scope/QD mount are almost impossible to find, the use of a military 4x Hensoldt
with reproduction mount would duplicate the original's size and performance at less than
half the cost.
The SIG AMT is one of the rarest military-style rifles in the United States. Imported in very limited numbers, the few which are available command a premium price and are normally found in excellent condition. Who would want to abuse such a fine example of the gun maker's art? Top notch machine work. solid design, excellent ergonomics, meticulous attention to detail and it host of similar thoughts crowd your mind when examining one. I should know - I bought my AMT after seeing it for only a few fleeting moments! Now, having been bitten by the SIG bug, how can I convince my wife to let me get that PE57 and mount a Gemtech suppressor on it..... and.......You get the idea.
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