These rifles are merely Spanish Model 1943 battle rifles that were converted to 7.62x51mm and modified to their present form for the purpose of creating a stop-gap battle rifle so they could enter NATO. The FR-8s were soon replaced with the Spanish CETME automatic rifles from which the German G1 was created. The FR-8s were kept for use with the Civil Guard and state police units. There were no purpose-built FR-8 rifles - they were all conversions.
Now for the bad news. These rifles should NOT
be fired with civilian .308 Winchester loadings! While these rifles might
be okay with surplus military ammo, the much higher pressures of the .308 Win will eventually wreck the gun - possibly dangerously so. These rifles were originally chambered for the 7x57mm Mauser cartridge which has a much lower pressure than even the 7.65 NATO loadings
. Also, the Spanish Mauser is not considered one of the better copies as the metallurgy of the times were iffy at best.
Here is some interesting reading on Spanish Mausers:
A substantial amount of information has been compiled concerning the safety and
reliability of the Spanish built FR-7, FR-8, and Guardia Civil rifles. The FR-7 and Guardia
Civil 1916 rifles are built on the 1893 pattern rifle. This particular design employs a two-lug
bolt system, as opposed to the 1898/1943 model rifles adopted by the Spanish
The 1893 pattern is a small ring Mauser action, 1893 pattern, with the two-lug bolt system.
The 1943 model employs the much-improved three-lug bolt system (two locking lugs and
a non-bearing safety lug). The model 1943 is a large ring rifle that was originally
chambered in 8X57. The FR-8 is a converted 1943 model. The FR-7 is constructed on the
1893 pattern. Many of both the 1893 pattern and 1898 pattern rifles were converted to the
7.62 x 51 mm NATO cartridge.
It should be noted here, that the small ring 1893 Mauser in 7 x 57 mm caliber was
designed for a maximum chamber pressure of 46000 cup. The 7.62 x 51 mm NATO round
topped with the standard 147 grain FMJ military ball bullet generates a maximum of
50,000 psi of chamber pressure.
The commercial .308 Winchester round topped with a 150-grain bullet generates an
average working pressure of 52,000 cup. The .308 Winchester’s maximum pressure is
limited to 55,200 cup, well above the pressure for which the 1893 pattern and the 1916
short rifle were designed. The 1898 type 1943 Mauser rifles are perfectly capable of
withstanding the higher pressures of the 7.62 NATO cartridges. However, a prudent
person would/should have this model Mauser and other military surplus weapons checked
by a competent gunsmith using the appropriate testing methods prior to firing them.
I currently own both an FR-7 and a Guardia Civil rifle (1916 Short Rifle). Both appeared in
excellent condition when purchased. However, upon having them examined by two local
Mauser experts, Cliff and Charles Houston of St. Petersburg, Florida, they found that the
headspace was beyond what is considered to be a normal range. This was determined by
the use of field and go/no gauges.
An additional portion of their examination of these two rifles concerns the steel used in the
construction of the 1893 pattern receivers of these rifles. The Spanish steel was of an
inferior grade (as compared to the original German produced models). Unfortunately, this
was a common practice of Spanish arsenal made rifles. Apparently they had a propensity
for disregarding generally accepted principals of metallurgy. The hardness of the two
receivers was determined through the use of a low tech, but thoroughly reliable device
called a Scleroscope. This simple, but reliable device has been in use in numerous types
machining and manufacturing industries for many years. It consists of a glass cylinder
marked with a Rockwell “C” scale, and a ¼ inch alloy ball of known hardness. The cylinder
is placed over the receiver, and the ball released. The level to which the ball rebounds to
is noted on the scale. Upon comparing the level to which the ball rebounded when
compared to dropping the ball on a piece of hardened tool steel it is readily determined
that the steel used in the manufacture of these two rifles is of an inferior (softer) grade as
opposed to rifles manufactured by German or Belgium companies.
An additional attribute of the Scleroscope lies in the fact that this device does not
penetrate the surface of the weapon being evaluated. Other devices penetrate the
surface, and therefore will mar the finish on the rifle being evaluated. These other devices,
while undoubtedly more definitive, are more cumbersome to use, and substantially more
costly. The Scleroscope is simple to use for the average person, is very portable, and
requires no batteries or sophisticated knowledge for its use.
The combination of a two-lug bolt system, a soft steel receiver, and a rifle chambered and
rebarreled for a cartridge that generates substantially higher chamber pressures than what
the original design was meant for can be a prescription for disaster.
Unfortunately, many of these rifles that were re-chambered to 7.62 NATO caliber and
marketed and advertised for sale in national publications as safe for use with both 7.62
NATO ammunition and .308 Winchester, with scant warning to the consumer. Therefore,
caveat emptor (buyer beware) is the watchword!!!
In order to safely shoot these rifles, I proceeded in the following manner. The 147 grain
FMJ bullet is removed from the NATO round and replaced with a 125 grain Sierra bullet
which Charlie Houston Danzac* coated, prior to loading them. This coating gives the bullet
a charcoal gray color, and is primarily used to prevent fouling in rifles, which are involved
in matches where a mornings shooting can be in excess of a hundred rounds. This also
reduces the friction of the bullet as it passes through the barrel of the rifle, which in turn
translates into a higher velocity at a correspondingly lower chamber pressure.
Next, the propellant charge of 47 grains of military spec powder was reduced by five
grains, giving the reconstituted round a final weight of 42 grains of powder, reducing
chamber pressure to approximately 39,000 psi.
The commercial .308 Winchester round received the same treatment, with corresponding
differences in the amount of reduction in the powder charge, due primarily to the
differences in the powder itself, and the fact the bullet weight was 150 grains.
An additional component of this project is to make certain that the spent brass from each
rifle is kept separate from each other. The spent brass of the NATO rounds are not being
reloaded due to the problem of their being loaded with Berdan primers. The
commercial .308 Winchester brass, which is loaded with boxer primers, is being reloaded.
The practice of keeping the spent brass separated is used to ameliorate the excessive
headspace in each rifle, since the brass cases will stretch sufficiently to achieve the goal
of tighter headspace.
There is another component in this process, after firing each round I carefully examine
each cartridge case for primer push back, case bulging, case splitting, or any signs of
stress to the receiver and bolt group.
Authors’ Note: I am not a gunsmith, nor am I an expert on Mauser rifles. I am merely a
person with a passionate interest in military surplus weapons.
Danzac = powdered tungsten disulfate
Rockwell Scale = A recognized medium used in surface hardness testing.
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Article written by: K.L. Cramer
Collecting and Shooting the Military Surplus Rifle (2006) - Surplusrifle.com