FN Self Loading Rifle 49 User Manual

							HOW THE P. N. SELF-LOADING 
RIFG WORKS 
The gun being ready for firing the action on the trigger 
releases the hammer. 
Under the tension of its springs, the hammer 
strikes the firing pin, which in turn strikes the primer of the cartridge 
and ignites the powder charge. 
1st. phase. - Tho bolt opoam uador the actton oi the gas. 
A small amount of gas escapes through a port bored in the 
bai rel and passes in the gas cylinder where it kicks the piston back. 
The piston drives the bolt carrier back. The bolt carrier unlocks the 
bolt and pulls it upwards to the rear. The extractor, which fits to the 
bolt, draws the empty shell out of the chamber. When the empty 
case is completely disengaged from the chamber its bottom 
strikes the ejector which ejects it to the right out of the gun. In 
its backward motion the bolt carrier cocks the hammer and 
compresses the recoil springs. 
2d. phase - The bolt ir cl04 uador the ton&n d rocotl sprbqm. 
As for any weapon firing with closed bolt, as soon as the 
bolt carrier has completed its backward motion, the recoil 
springs drive it forward. The bolt carrier itself forces the bolt 
forward. The bolt drives a cartridge ahead out of the ma9azine 
and pushes it into the chamber. The bolt is then locked downwards 
in the receiver by the action of the bolt carrier. 
DRAILS OF OPERATION 
1. THE ENGINE 
In addition to the barrel (lA), the components of the en9ine 
are : the gas cylinder (1Bl. the piston (121 and its sprin9 (13, the 
gas cylinder plug (81 and the gas adjusting sleeve (61. 
Stnqlo rhot md full automattc ftm 
In the F. N. Self-Loading Rifle, the utilization of gas presents 
several outstanding features : 
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							Fiq. I. 
a) Short gas cyhcler. - 
The 9as cylinder (IB) is a very 
short tubular element, easily cleaned, after the gas cylinder plug 
and the piston have been removed. As experience has shown that 
the gas acted on the piston in the way of a hammer blow, without 
any expanding, the ions cylinders which were generally, used in 
gas operated rifles, have consequently become useless. 
b) Gas escape. - After they have acted hi the way of a blow 
on the piston, the gas escape outside throu9h a slot (Al located on 
top of the front end of the 9as cylinder. 
The handicap of. the 9as operated weapons betn9 the foulin9, 
the advantage of this 9as escape system is the permanent 
sweepin outwards of the combustion residues. 
c) Gas regulatioa. - The size of the slot for the escape of gas 
and its location are such, that when it is completely open the 
pressure exerted by the gas on the piston is insufficient to operate 
the mechanism. That is the point where the regulator intervenes. 
The regulator is built from a simple’threaded sleeve (6). screwed 
around the gas cylinder. When the sleeve is screwed in, the 
openins for gas escape decreases and consequently the thrust of 
the gas on the piston is growinq, a 9ood functtonin9 of the rifle, 
without undue fati9ue for the mechanism, is thus ensured. The 
gas regulation is carried out by the manufacturer, when the rifle 
is assembled. It may not be changed by the soldier. The regu- 
lator has therefore been intentionally located under the hand9uard. 
On the other hand, it is a very easy task for the armourer to refix 
the 90s regulation if. eventually, another resulation has to be 
adooted. either in order to use a lot of soecial ammunition. or to 
use-the rifle in a country in 
completely different which the atmospheric conditions are 
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							d) Iodm of the pbton. - The piston (12) and the bolt 
carrier (27) are located in a-straight line, without any COtUl8CtiOn. 
The return of the piston is performed instantly under the action 
of its own spring (13) without the interference of the return springs. 
It is owing to this original feature that it is possible to load the 
gun the same way as a repeatinb rifle. 
Turning 18(r the qas cylinder plug (8A1, cuts the inlet of the 
gas. The piston does not transmit any thrust on the bolt carrier. 
The rifle can then be used like a repeater by pulling 6’18 bolt 
carrier by hand. 
2. HOW THE OPENING AND THE CLOSING 
OF THE MECHANISM IS OPERATED 
The components acting in this phase are : the receiver USAl 
or (215Al the bolt (21). the bolt carrier (271 or (227), the return 
spring (67A - 2 pieces - and DI, the cover (651. 
The bolt carrier (271 or (223 moves along the receiver USA) 
or (215A). It is pushed rearwards by the piston (12) and is forced 
forwards by the P-piece return spring (67A). Th8 bolt is in one piece 
and its positive locking is performed when its flat surface at the 
rear is in line with the locking shoulder mad8 in treated steel and 
pressed in the receiver at the rear of th8 magasine. The respective 
motions of the bolt and of the bolt carrier are controlled as 
!ollows : 
When the cartridge is fired fposition 11, the bolt is in its 
locking position A and is located in this position by the contact of 
surface B of the bolt carrier. 
n8-m may b8 schemed in three phases : 
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							Fig. 2. 
First Phase (position 1 to position ‘2) : Break of contact of the 
surface at B. The bolt is still locked (A) while the pressure in 
barrel is dropping. 
F&J. 3. 
Suomd b (position 2 to position 3) : Unlocking of the 
mechanism. The contact between surfaces C forces the bolt up. 
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							Position 3 
Flq. 4. 
‘IMrd Phase (position 3 to position 4): Direct opentnq. The 
bolt and the bolt carrier are travellinq together rearwards owinq 
to the contact of surfaces F. 
When the parts are stopped at the rear, they are in position 4, 
the double return spring is compressed. 
Flq. 5. 
The cl- of the me&w may be schemed as below 
in 3 phases : 
Fowth phase (position 4’to position 5)‘: Clorinq of the mecha- 
nism. The bolt carrier pushes the bolt forwards owing to the 
contact of surfaces G till the bolt is rtopped by rear end of the 
barrel. 
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							Position 5 
Fh. 6. 
FWh Phase (position 5 to position 6) : L.ockinq of the mecha- 
nism. At this moment the slope H forces the rear part of the 
bolt downwards, in the lockinq position. 
Position 6 
Flq. 7. 
Sixth m (position 6 to position 1). Confirmation of the 
lockhq. The bolt carrier continues its movement forward and the 
bolt is maintained in the locking position by the surfaces B. 
The repeatinq cycle is identical with the automatic cycle. 
k;trnaz receive the thrust d the piston, the bolt carrier is operuted 
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							3. FEEDING - EXTRACTION - EJECTION 
The additional parts actin@ in this phase are : the 
(22) and the elector (51). extractor 
a) B&action of the case. - The extractor which is 
. fitted on 
the right side of the bolt performs this operation by direct extraction 
for the wlthdrdwal of the case (see above : 3d phase - posittin 3 to 
position 4). 
b) Ejociioa - The ejector is of the fixed type and is fitted 
in the trigger quard at the rear of the magazine. It protudes in a 
groove cut at the left and in the underside of the bolt. At the end 
oi the rearward motion (3d phase). the case strikes against the 
ejector and being compelled to pivot around the extractor is ejected 
riqhtwards. 
lhere exist other types of ejectors but the type choosen for 
the F. N. rifle has the great advantage to help the shooter to know 
how his rifle is working, as the ejection occurs nearly at the end 
of the travel of the bolt to the rear at the moment when its is at 
the point to b3 stopped against the rear wall of the receiver, 
. . . 
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							very eaa to ensure, with a thorough knowledge of the where- 
abouts a perfect functioning of the rifle. 
With electors which are fitted elastically on the receiver this 
cannot be reached. 
c) lntroductlon of a cart&go. - The bolt has two ribs on its 
lower side, these ribs, when the bolt is closing (see above 
4th phase, - position 4 to position 5) push alternatively the left 
or the right side cartridge directly into the chamber. 
As soon as the cartridge leaves the lips of the magazine, it 
is caught by the extractor and moves with the bolt. This charac- 
teristic, taken from the best repeaters, presents several advantages : 
1. The double feeding is impossible ; 
2. The extractor is spared, because it has not to 90 over the 
rim of the cartridge as it is the case when the cartridge is first 
introduced into the chamber. 
3. The closing is smoother. It ought to be mentioned that the 
closing is only due to the energy stored during the recoil in the 
springs and not to a positive mechanical action. 
4. HOW THE FIRING ACTION WORKS 
For rifles firing only single shot, the firing action is fitted in 
the trigger guard (301 and consists of : 
- The hammer (31Al with its springs (34A-Bl and its guide 
(31Bl which serves also as a cocking indicator. 
- The trigger (36) which serves as the principal sear. 
- The rear hook acting as the auxiliary sear (391. 
- The safety (46). 
The firing of the cartridge occurs by means of a firins pin (in 
two parts) (24-281 housed in the bolt. 
The characteristics of the mechanism are as follows : 
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							J 
Fw 9 
Fiq. 10. 
Action of rifle ftrt.119 only stn910 shot fire. 
a) Sopcuotion of the shots iu stn910 shot ftro. - The device 
which allows to fire exclusively shot by shot, has been taken over 
from an outstandmg weapon (The Browning automatic shotgun). 
Since more than 50 years It ensures a perfect functioning to this 
popular gun. 
The hammer (31A) is forced backwards by the recoil of the 
bolt and bolt carrier and it is in any case caught by the double 
hook, which is made up by the front end of the trigger acting 
as the main sear (36) and by the linked hook acting as the 
auxiliary sear (39). 
Indeed 11. per chance, owing to the effect of the recoil the 
fmger of the shooter has left the trigger at the moment the hammer 
1s sent backwards, the hammer is directly caught by the main 
sear (36). 
If on the contrary, which is generally the case, the trigger 
1s still depressed by the finger, the hammer is caught by the 
auxiliary sear (39) which has been put on its way by the motion 
of the trigger. The hammer is caught in this position as long as 
the trigger 1s depressed. 
In order to fire the next shot one has first 
to release the trigger. - The hammer is then released by the auxi- 
liary sear (39) but is at once and uncrvoidably caught by the r -in 
sear (36). 
To fire again one has to depress the trigger once more. 
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CID