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This work has been compiled from the paper presented during the 12th International Armament Conference on Scientific
Aspects of Armament & Safety Technology, Jachranka, Poland, September 17-20, 2018
New Cartridge Design for Assault Rifle
Peter LISÝ*, Martin DANIEL
Department of Mechanical Engineering
Armed Forces Academy of Gen. M.R. Štefánik,
Demänová 393, 031 01 Liptovský Mikuláš 6, Slovak Republic *Corresponding author’s e-mail address and ORCID:
[email protected]; https://orcid.org/0000-0001-8721-2660
Received by the editorial staff on 18 May 2018
The reviewed and verified version was received on 02 June 2020
DOI 10.5604/01.3001.0014.1989
Abstract. The article deals with the possible design of a new cartridge for an automatic
assault rifle. This hypothetical design is based on the analysis of five automatic assault
rifle cartridges which are currently used in armies: 7.62×51 mm NATO, 7.62×39 mm
M 43, 5.56×45 mm NATO and also another two cartridges which are under testing both
6.8×43 mm Rem. SPC and 6.5×38 mm Grendel. The analysis of a new cartridge including
internal ballistics, external ballistics, and terminal ballistics energy disposed to the target
upon an impact is introduced in the article. The goal was to create a cartridge that would
have better ballistic performance than 5.56×45 mm NATO and it would still possess
enough accuracy of fire and speed, so that it could dispose at least minimal kinetic energy
necessary to incapacitate individuals. Also it is important to maintain the constancy of
this effect for the long distance shooting, somewhere around 500 m, during battles in an
open area (effective range of 5.56×45 mm automatic assault rifles is normally of about
300 m what only suffices in close quarter battles).
PROBLEMS OF MECHATRONICS ARMAMENT, AVIATION, SAFETY ENGINEERING
ISSN 2081-5891 11, 2 (40), 2020, 9-24
PROBLEMY MECHATRONIKI UZBROJENIE, LOTNICTWO, INŻYNIERIA
BEZPIECZEŃSTWA
P. Lisý, M. Daniel 10
To achieve it, the bullet must have the higher sectional density than the 5.56×45 mm
cartridge. The sectional density reflects the capability of bullet to penetrate through the
human tissue within the requirements of wound ballistics. Based on the analysis, the value
of sectional density should be approximately of 0.21 g/mm2. The function of fully
automatic firing depends on the size of the recoil energy of a weapon which is also related
to the muzzle energy that cannot surpass the amount of 2 500 J. The new cartridge design
is based on the 6 mm Scenar bullet (FMJ - Full Metal Jacket bullet with a weight of 5.8
g) made by the Lapua Company. All the ballistic parameters must be within the intervals
of strength and construction possibilities of small arms ammunition. To create a possible
variation of the mentioned cartridge where its bullet will be powered by a nitrocellulose
propellant (originally made in Czech Republic), a new cartridge case will be created.
Keywords: ammunition for automatic assault rifles, ballistics
1. INTRODUCTION
A mixture of the close-quarter combat and long-range contacts again raised
questions of the stopping power of NATO ammunition. The standard NATO
ammunition with a green tip is failing to stop attackers. Also, it cannot fight with
calibre 5.56×45 mm NATO (range up to 600 m) against 7.62×54 R mm Russian
calibre which is using a light machine gun up to 900 m [1]. Majority of fighting
contacts occurs at either very close range or at the ranges between 500 m to 900
m (Table 1).
Table 1. Fighting contacts [2]
It is clear from Table 1 that these ranges are possible to cover only with
established weapon 7.62×51 mm general purpose machine gun. The calibre
5.56×45 mm has a lack of the reaching the enemy at those ranges because
this calibre is sufficient only at the proper range, but for the longer ranges
7.62×51 mm calibre is necessary. Here is a needful research for the higher
performance rounds with a higher efficiency at the longer ranges.
The waiting is, that next generation of assault rifle to replace the 5.56 mm SA80
around 2020 [3].
New Cartridge Design for Assault Rifle 11
The 5.56×45 mm NATO cartridge for assault rifle and a light machine gun
is under criticism due to extensive combat experience. This calibre was always
controversial choice due to a small size and a lack of power [4]. The complaints
are from British soldiers, too. It is mainly for:
- poor long-range effectiveness;
- erratic efficiency even at short-range;
- a lack of suppressive effect;
- poor barrier penetration.
Accordingly, from German troops are complains on:
- lack of stopping ability;
- penetration.
The experiences both from Iraq where is the urban fight and Afghanistan
where are the long-range engagements mentioned that achieving the best
compromise will involve several variables [5]:
- hit probability (a function of trajectory, flight time and wind drift);
- required maximum range;
- terminal effectiveness (against soft and hard targets) at different ranges;
- acceptable cartridge weight and recoil.
The answer for the raising of requirements on the base of complex
operational environment for the international armed forces activity is in the
ultimate consequence graduation requirements on the alternative design weapon
and ammunition with the trend on improvement the mobility (manoeuvrability),
precision and stopping effect. At the present time, it is going the research in
design of small arms including implementation of shorter barrels and carbines for
the close quarter battle and personal defence weapon. Accordingly, it is going the
research for alternative calibres from the reason of optimization of their weight
and stopping effect, spread of applicability of suppressors for reduction of
unmask symptoms and area of integrated fire system for improvement in
precision on the lowest tactical level. The operational requirements were
determined on the conference “Future Soldier Technology” in London on the 3rd
of March 2018 [6]. North Atlantic Treaty Organization, as an alliance, is trying to implement its
common ammunition into the armies which are being the part of the organization.
Nowadays, NATO possesses two main cartridges for assault rifles which are
being normally used in asymmetrical wars in the Middle East – 5.56×45 mm and
7.62×51 mm. The close quarter battles offer better opportunity for using the
5.56×45 mm cartridge because it has enough ballistic performance for firing at
short distances but it lacks the capability of incapacitating an individual at longer
distances (more than 300 m).
However, also its behaviour on a short distance is like an arrow, i.e.,
a small bullet with high speed overruns a body and makes a small permanent
cavity which means that the bullet does not transfer enough kinetic energy to the
body and does not stop to fight the individual.
P. Lisý, M. Daniel 12
On the other hand, the 7.62×51 mm cartridge over the fact of much better
ballistic performance appears to be a twice heavier than the smaller cartridge of
5.56×45 mm (Table 2). Also, from Table 2 we can compare other cartridges’
parameters for assault rifles and Fig. 1 shows the designs comparison of the
mentioned cartridges.
Table 2. Parameters of assault rifles cartridges [7]
Fig. 1. Cartridges (left) 7.62×39 mm M43; 7.62×51 mm NATO; 5.56×45 mm NATO;
6.8×43 mm Rem. SPC; 6.5×38 mm Grendel [7]
Cartridge
7.62×39 mm
M43
FMJ
7.62×51 mm
NATO
FMJ
5.56×45 mm
NATO SS109 FMJ
6.5×38 mm
Grendel
6.8×43 mm
Rem. SPC
FMJ
bullet weight
mq [g] 7.9 9.33 4 5.8 7.45
muzzle velocity
vm [m/s] 730 800 906 823 785
muzzle energy Em [J]
2 105 2 986 1 642 1 964 2 295
sectional density
SD [g/mm2] 0.173 0.205 0.165 0.175 0.205
barrel length
lbar [mm] 415 450 450 368 410
effective range L [m]
800 600 600 600 300
cartridge
weight – mc [g] 16.3 25.4 11.8 14.7 16.8
New Cartridge Design for Assault Rifle 13
The performance of the different calibres can be compared by their kinetic
energy value. In Fig. 2, we can see the courses of the bullet energy Eq vs the
distance L for the four cartridges listed in Table 1, where it is evident that the
more aerodynamic bullet of the 6.5×38 mm Grendel, but with the weight of 8 g,
keeps the kinetic energy for the long distance the best. At the distance of 600 m
it has approximately the same energy as the 7.62×51 mm bullet, 1.5 times higher
energy like the 6.8×43 mm Rem. SPC and 3.3 times like the 5.56×45 mm. But,
the 8 g 6.5×38 mm Grendel bullet has the muzzle energy of 2528 J and the
sectional density of 0.24 g/mm2 which are both too high for keeping a sustainable
fire due to the high recoil energy Er = 5.06 J for 4 kg heavy weapon.
Fig. 2. Bullet energy value for different calibres [8, 9]
For alliance like the NATO, it would be better to provide material supply
just for one type of a cartridge, which would possess the ballistic performance
somewhere between these two types of the rounds – it means better the ballistic
performance (accuracy of fire, muzzle velocity, energy disposed to target upon
impact) also for longer distances (target distant of about 500 m, up to 600 m).
And the individual could be still a capable to carry at least the same number of
rounds in the magazine for 5.56 mm automatic assault rifle. Here, there exist
some intentions which offer an alternative for the common ammo like 6.5×39
mm Grendel or 6.8×43 mm Rem. SPC, but we tried to create a possible cartridge
with 6 mm calibre.
P. Lisý, M. Daniel 14
2. CARTRIDGE DESIGN
At creating a new cartridge design for the middle ballistics performance it is
important to achieve a proper rate between the performance at long range and
recoil of automatic assault rifle (AAR), i.e., for shooting with controlled full-auto
fire. From Table 2, we can see that for the lesser recoil AAR, the calibre could be
less than 7 mm and from another side for the better stopping effect, the calibre
could be bigger than 6 mm include. When the bullet sectional density is bigger,
the bullet will has more performance at the longer distance but the muzzle energy
could not exceed the value of 2 500 J for the recoil reason. At present, it is the
requirement to use the same cartridges for AAR-s and light machine guns.
One of the main parts of a cartridge is a bullet which is a cylindrically shaped
lead or alloy that engages with the rifling of the barrel. The bullet consists of
a steel penetrator and a copper alloy jacked (the copper alloy reduces barrel
wearing and helps to prevent the bullet from striping or jumping the rifling during
firing). To obtain high velocities, which we need for the military applications, the
full metal jacketed bullet was chosen.
The bullets are mainly characterised by the ballistic coefficient which
determines how well the bullet can maintain a velocity. The bullets with the less
ballistic coefficient maintain the velocity better. The ballistic coefficient BC can
be calculated:
𝐵𝐶 =𝑖∙𝑑2
𝑚𝑞∙ 103 [m2/kg] (1)
where i is the bullet´s form factor; d – is the calibre; mq – is the bullet weight.
Very important characteristic of the bullet, which is applied not only in
external ballistics but also in internal and terminal ballistics, is the sectional
density - SD. The sectional density also defines range, graphic of bullet path, and
duration of bullet flight. With increasing the sectional density upon firing with
the same angle, the range is longer, and the path of flight is flatter. The sectional
density can be calculated:
𝑆𝐷 =4∙𝑚𝑞
𝜋∙𝑑2 [g/mm2] (2)
Both the BC and SD have influence on the range and effect on the target. To
reach the enough ballistic performance, also for the longer distances, there was
chosen the Lapua Scenar bullet with the calibre of 6 mm and weight of 5.8 g (Fig.
3), which is used at present by the world´s top competitors and it gives the superb
results at the long ranges shooting [10].
New Cartridge Design for Assault Rifle 15
Fig. 3. Lapua Sierra 6 mm calibre Scenar [11]
This bullet has the ballistic coefficient for long range (G7) equal to 9.61
m2/kg, while the 5.56×45 mm NATO has the ballistic coefficient (G7) of 13.42
m2/kg. Figure 4 shows the difference of the drag bullet coefficient in dependence
of the Mach number for 6 mm Scenar bullet for the both, ballistic coefficient G1,
which is used usually, and G7 which is used for a long range.
Fig. 4. Drag bullet cx vs Mach number for 6 mm Scenar bullet [11]
From Figs. 5-6 we can see dependence, the 6 mm Scenar bullet energy Eq,
the speed vq, the deviation wd and the path qp versus the distance L. Figure 5 shows
the bullet parameters dependences at 4 m/s side-wind. Figure 6 shows the bullet
paths at the scope of 40 mm above the centre line of a barrel at three different
rifle aiming on 100 m, 300 m, and 600 m, where we can see the impact points
above or below the line of sight.
P. Lisý, M. Daniel 16
Fig.5. Dependency bullet parameters vs distance at 4 m/s side-wind [10]
Fig.6. Bullet path vs distance at scope 40 mm above centre line of barrel [10]
The Lapua firm is best known for its experiences and better possibilities of
the manufacture and the offer of a new ScenarL bullet (Fig. 7). The differences
between both the Scenar and ScenarL bullets are these that new ones have a new
line, better concentricity of a jacket wall, a less weight variation, and
a dimensional uniformity and other parameters are the same. These new things
offer the better possibility of a fire precision.
New Cartridge Design for Assault Rifle 17
Fig. 7. Comparison Scenar and ScenarL bullets [10]
The chosen ScenarL bullet, for a possible military cartridge, is capable of
maintaining the velocity in a better way than the bullets mentioned in Table 2 and
it would strongly affect the target and more deeply penetrate into the armour or
human tissue. This bullet at the range of 548 m has the velocity of 529 m/s and at
zero speed of wind has the deviation of 72 mm (Fig. 8). Because the cartridge
case has no good proportions, mainly its diameter, therefore we design a new
cartridge case.
Fig. 8. Deviation of 6 mm ScenarL bullet [12]
In Figure 9, it is a design for the new cartridge case which was created for 6
mm bullet ScenarL with its muzzle velocity of 802 m/s at 372 mm barrel length.
The overall length of the calculated cartridge case is 44.06 mm. In Fig. 10 there
are compared two cartridges, i.e., the original cartridge design for 6×40 mm
ScenarL, made by LAPUA company and the new cartridge case for the same
bullet designed by us.
P. Lisý, M. Daniel 18
Fig. 9. Cartridge case for the new cartridge
Fig. 10. Comparison two cartridges 6×44 mm new and 6×40 mm
Lapua ScenarL [13]
It is evident from this comparison that the new cartridge is slimmer, and its
maximum diameter of the cartridge case is 10.9 mm and the original maximum
cartridge case diameter is 11.96 mm. The overall length of the cartridge is 61.875
mm for the new one and 61.2 mm for the original one.
The calculation of internal ballistics for the new cartridge was made by
thermodynamic interior ballistic model. The classical internal ballistics equations
can be written as follows:
d𝑧
d𝑡=𝑢1𝑒1𝑓(𝑝)
𝜓 = 𝜅𝑧(1 + 𝜆𝑧 + 𝜇𝑧2)
𝜓 = (1 +𝑒1𝑙) 𝑧 −
𝑒1𝑙𝑧2
𝑝𝑥 = 𝑝𝑞 {1 +1
2𝑘𝜒
𝑚𝜔
𝜑1𝑚𝑞
[1 − (𝑥
𝑙𝑐ℎ𝑙𝑞)
2
]}
(3)
New Cartridge Design for Assault Rifle 19
where:
z is the propellant relative burnt thickness;
u1 is the unit speed of burning;
e1 is the half thickness of propellant;
f(p) is the pressure function;
κ, λ, and μ are the internal ballistic parameters related to propellant shape;
l is the length of propellant grain;
px is the immediate pressure inside a barrel;
pq is the pressure at the base of projectile;
kx is the coefficient of loses;
mω, mq are the propellant and projectile weights, respectively;
φ1 is the power coefficient;
x is the immediate distance from base of chamber;
lch is the chamber length;
lq is the immediate path projectile.
The bullet was taken 6 mm Lapua ScenarL with the weight of 5.8 g, how it
was mentioned earlier, and a powder gun was taken the nitrocellulose propellant
S-053 which is made in Czech Republic. This propellant has been used for
a long-time for 7.62 mm assault rifle, both in Slovak and Czech Republic. The
parameters of S-053 propellant are the force f = 1.0132·106 J/kg and the co-
volume α = 0.9242 m3/kg, and is reliable. The propellant is made in the form of
short tubes with a deterrent which burn at the first half period as progressive and
the second half as degressive. The maximum computed pressure was 327 MPa
and the muzzle velocity was 802 m/s. We could suppose that this pressure will
make a lower recoil force and less disturb the barrel to vibration than the pressure
of the 7.62×51 mm NATO (420 MPa) cartridges.
From Table 3, we can compare 6 mm ScenarL parameters with further
cartridges. The parameters from Table 3 show that the 6×44 mm new cartridge
with the ScenarL bullet has the highest ballistics coefficient, which supposes the
better bullet stability during a flight. The bullet has the good sectional density
what means, that it will be the better transfer of a kinetic energy to the human
body, i.e., it will have the better stopping power. Moreover, only the 372 mm
long barrel for an assault rifle will give the good possibility for
a manoeuvrability and the bullet velocity of 802 m/s also will give the possibility
of the shoot up to 600 m with a good precision, as is evident from Fig. 8. The
shorter barrel is stiffer than the longer one and a vibration is smaller during the
shoot, therefore the shorter barrel is more precise [14, 15, 16]. The bullet muzzle
energy of 6×44 mm is higher than of 5.56×45 mm, but enough smaller than of
7.62×51 mm NATO.
P. Lisý, M. Daniel 20
We can compare also from Table 3 the recoil energy Er when we will
suppose the weight of 4 kg of an assault rifle for each mentioned calibre. From
this, it is evident that the new cartridge will have very low recoil energy what is
good for an automatic fire.
Table 3. Basic parameters of selected cartridges [7, 17, 18]
Cartridge mq
[g] BC G-7
[kg/m2]
SD
[g/mm2]
Vm
[m/s]
Em
[J]
Er
[J]
lbar
[mm]
lcar
[mm]
7.62×39 mm
M43 7.9 13.29 0.173 730 2 105 4.16 415 56.00
7.62×51 mm
NATO 9.33 9.95 0.205 800 2 986 6.96 450 69.90
5.56×45 mm
NATO 4.0 13.42 0.165 906 1 642 1.64 450 57.40
6.5×38 mm
Grendel 5.8 11.02 0.175 823 1 964 2.85 368 57.50
6.8×43 mm
Rem. SPC 7.45 12.48 0.205 793 2 342 4.26 457 57.40
6×44 mm
new 5.8 9.61 0.205 802 1 865 2.71 374 61.875
The loss of the bullet velocity and energy towards the target is influenced
mainly by the ballistic coefficient and amount of the sectional density. For the
new cartridge, the analysis of outer ballistics of the ScenarL bullet by the
PM_Ballistics program was performed.
From Fig. 11 we can see the courses of three parameters – vq, Eq, and wd up
to the distance of 600 m with the zero speed of wind. In Fig. 12 there is shown
the decrease in bullet energy for the two NATO calibres and for the new ones
versus the distance up to 500 m. The new calibre has the bigger kinetic energy
than 5.56 mm calibre and at the distance of 500 m the difference of almost 200 J
is bigger for the new one, despite the fact that 5.56 mm bullet has the higher
muzzle velocity but at 450 mm long barrel against 374 mm long barrel for the
new cartridge.
In Fig. 13 there are shown the 6 mm Scenar bullet paths at the scope of 30
mm above the centre line of the barrel at three different assault rifles aiming at
100 m, 300 m, and 600 m.
Also, from Table 4 we can see, that when we want to defeat 3.5 mm steel
plate at the range of 600 m, how many kinetic energy Edefeat we need for it. This
is common for core bullets made from lead, brass, and steel. The minimal kinetic
energy Ewound, necessary to incapacitate individuals, without body armour, is 82
J and the total kinetic energy Etotal for defeat both is stated also in Table 4.
New Cartridge Design for Assault Rifle 21
Fig. 11. Bullet energy, velocity, and deviation vs distance for the new cartridge
Fig. 12. Decrease in bullet energy vs distance
Fig. 13. Bullet path vs distance at a scope of 30 mm above the centre line of a barrel for
the new cartridge
P. Lisý, M. Daniel 22
Table 4. Kinetic energy for different calibres necessary
for defeat individual at 600 m [19]
Calibre
[mm]
Edefeat
(3.5 mm steel plate)
[J]
Ewound [J]
Etotal [J]
5.56 565 82 647
6 638 82 720
6.35 694 82 776
6.5 722 82 804
6.8 776 82 858
7 806 82 888
7.62 910 82 992
3. CONCLUSIONS
Based on the new cartridge design for an automatic assault rifle, the
following conclusions can be drawn:
1. Better ballistics performance like 5.56×45 mm NATO and hereby less
performance to compare with 7.62×51 mm NATO cartridge.
2. Sufficient precision in accordance with the chosen bullet design, also for
the long-range shooting.
3. Sufficient precision due to the smaller barrel vibration.
4. Sufficiently low recoil for the automatic fire than 7.62×51 mm NATO
which makes it possible to shoot with the observation fight situation.
5. Reduction of the cartridge mass against 7.62×51 mm NATO but the new
cartridge design 6×44 mm has the same sectional density and ballistic
coefficient.
6. Need to make both, the new cartridge case and barrel with a chamber
for 6×44 mm cartridge and to make real testing.
7. To reach the total kinetic energy necessary for the range of 600 m for the
calibre of 6 mm, it is needed to extend a barrel for the new cartridge design.
8. This article is only the small contribution to solve the problem with
a new military calibre how it is stated in the article [20]: “The case for
a new military calibre is a popular but controversial topic that arouses
interest and emotion out of all proportions to the importance of small arms
within Army´s.”
New Cartridge Design for Assault Rifle 23
FUNDING
The authors received no financial support for the research, authorship, and/or
publication of this article.
REFERENCES
[1] Williams G.A. 2009. “The great calibre conspiracy”. Jane´s Defence
Weekly, 11th September, 2009.
[2] US Army ARDEC. UK MoD /British Army analysis 2009-2014. Available
on the Internet: <https://uklandpower.com/2017/11/29/the-case-for-a-new
military-calibre/>
[3] White A. 2009. “UK forces take on small-arms lessons from Afghanistan”.
Jane´s International Defence Review. October, 2009.
[4] Williams G.A., N. Drummond. 2009. “Time to bite the bullet over
under-fire ammo”. Jane´s Defence Weekly. 11th November, 2009.
[5] Williams G.A. 2014. “Design dilemma: small arms and ammunition
Development”. Jane´s International Defence Review. September, 2014.
[6] White A. 2018. “Personal effects”. Jane’s Defence Weekly. 2nd May,
2018.
[7] Caras I. 1995. Ammunition for small arms (in Czech language). Prague,
Czech Republic: ARS–ARM.
[8] AR 6.5 Grendel vs. 5.56 vs. 300 AAC Blackout. Available on the Internet:
<https://www.ingunowners.com>
[9] Williams G.A. 2012. The next NATO rifle and machine gun
cartridge? Available on the Internet:
<https://www.ingunowners.com/forums/long-guns/ 251101-ar-6-5grendel
-vs-5-56-vs-300-aac-blackout-4.html>
[10] Lapua Product Catalog, 2015. Available on the Internet: <http://wp-
content/uploads/Katalog-Lapua-2015-ProductCatalog. pdf>
[11] Bryan L. 2008. Applied Ballistics for Long Range Shooting. Applied
Ballistics, Cedar Springs.
[12] Lapua Scenar-L Bullets 243 Caliber, 6 mm (243 Diameter). Available on
the Internet: <https://www.midwayusa.com/product/492294/lapua-scenar-
l-bullets-243-caliber-6mm-243-diameter-90-grain-hollow point -boat-tail-
box-of-100>
[13] Available on internet:<http://www.lapua.com/en/ammunition/calibers/
6mm-br-norma>
[14] Lisý Peter, Mário Štiavnický. 2011. Influence of the barrel oscillations into
accuracy of small arms. In Proceedings of International Conference on
Military Technologies 1737-1744. Brno, Czech Republic.
P. Lisý, M. Daniel 24
[15] Štiavnický Mário, Peter Lisý. 2013. “Influence of Barrel Vibration on the
Barrel Muzzle Position at the moment when Bullet Exits Barrel”.
Advanced in Military Technology 8 (1) : 89-102.
[16] Lisý Peter, Mário Štiavnický. 2014. “Weapon Barrel and its Additional
Accessories”. Problemy mechatroniki. Uzbrojenie, lotnictwo, inżynieria
bezpieczeństwa - Problems of Mechatronics. Armament, Aviation, Safety
Engineering 5 (1) : 9-24.
[17] 6.5 Grendel with 90 gr TNT® HP. Available on the Internet:
<https://www.speerammo.com/media/d7ece5cb4bbe453392b2a7305a381
83e.pdf>
[18] Nathaniel F. 2015. Not So Special: A Critical View of the 6.8 mm SPC.
Available on the internet: <http://www.thefirearmblog.com/blog/
2015/04/04/not-so-special-a-critical-view-of-the-6-8mm-spc/>
[19] Daniau E. 2017. Towards a “600 m” lightweight General Purpose
Cartridge. DGA Techniques Terrestres, Bourges, 2017. Available on the
Internet: <htpp://quarryhs.co.uk/Emeric2017.pdf>
[20] Drummond N. 2017. The Case for a New Military Calibre.
Available on the Internet: <https://uklandpower.com/2017/11/29/the-case-
for-a-new-military.calibre.calibre/>.