AIRCRAFf ARMAMENT

The Second World War aircraft gun controversy

Which was themost effective form of combat-aircraft armament duringWorld War Two?Abatteryof
small-calibremachine-gunscreating ahail of bul lets?
or fewer but heavier cannon,perhaps capable
of deliveringadecisive blow with each shell? ANTHONY G. WILLIAMS weighs upthe pros and cons
-

.-

ABOVEThe Oewoitine
0.520, with its four 75mm
wing-mounted machine
guns and a fast-firing
Hispano-Suiza moteurcanon, was the best fighter
in the French inventoryat
the outbreak of war.
OPPOSITE,TOP Armourers
replenish the magazines of
the two nose-mounted
050in and four wingmounted 030in machineguns of a Bell Airacobra of
601 Sqn, RAF. The barrel of
the 20mm cannon, firing
through the propeller hub,

IS conspicuous.

58

HE SECOND WORLD WAR stimulated an

important advance in aircraft gun armament. The fighters of most combatant
nations began the wa r w ith a few riflecali bre machine-guns (RCMGs) of 7'5- 8mm calibre, but, by the end of the conflict, cannon of
20mm or greater ca libre we re standard. The
one exception was the USA, which relied
overwhelmingly on the 12 7mm (0'50in) M2
Browning heavy machine-gun (HMG) . Students
of arma ment history conti nue to argue: why did
this happen, and we re the Am ericans right?

EARLY FIGHTING
In 1939 the RAF's new Spitfire and Hurricane
fighters we re remarkable for their heavy battery
of eight wing-m ounted 0303in (7'7mm) RCMGs;
tw ice as powerful as that of any other major
fighter. In con tras t, Germa ny's Luftw affe had
been watching the French use of engine-mounted
cannon. In 1932 this resulted in a requirement
for a fighter wi th two RCMGs or a single 20mm
cannon. The weapon considered was the large,
very powerful but slow - fi ring RheinmetallBorsig MG C/30L, firing through the propell er

hub. An initial experiment w ith a prototype

Heinkel He I 12 in the Spani sh Civil War showed
that this installation w as unsatisfactory for aerial combat, though effective in gro und attack.
Germany then w ent to the opposite extreme
and selected the small, low-velocity Swiss Oerlikon FF 20mm cannon for development. A
modified version, the MG-FF, was put into pro duction by Ikari a Werke Berlin, and entered
Luftw affe service . Initial attempts to fit this as
an engine gun ran into reli ability prob lems, so
the Messerschmitt Bf 109E-3 of 1939 carried
tw o MG-FFs in the w ings and a pair o f 792mm
MG I 7 guns synchronised to fire through the
propeller disc. However, many Bf 109s we re still
armed with four RCMGs at the start o f the w ar.
The Battle of France caught the French with
few fighters capable o f dealing with the Bf 109s.
Most French fighters carried a mixtu re of 20mm
ca nnon and RCMGs; the best w as the Dewoi tine D.520 w ith its four wing-mounted 75mm
MAC34 M39 MGs and the powerful, fast-firing
Hispano-Suiza HS.404 m oteur canon. The USAbuilt Curtiss Hawk H-75A, with four or six 75mm
FN-Browning guns, wa s too lightly armed.
One lesson o f early fighting was that the RAF
fighters' battery o f RCMGs was less effective
than expected. Although the eight guns between them fired no few er than 160 ro unds per
second (r.p.s.) . they we re initially adjusted to
concentrate their fire at the long range of 400yd,
which led to the bu ll et strikes being spread
across the target at shorter ranges. As selfsealing fuel tanks and armour became much
more common during 1940, it proved necessary
to concentra te fire at much closer ranges.
The pro blem was that the small bullets fi red
by the RCMGs could not carry enough incendi ary or explosive to guarantee success, and also
had insuffi cient penetrati on to defeat armour
reli ably. A series of gro und tests carried out by
th e British , firin g at a redund ant Bristol
AE RO PLANE, SE PTEM BE R 2004

Blenheim from 200yd to the rear wi th various

British and German guns and ammunition,
revealed that the 0303in incendiary B Mk VI
bullets w ould set light to a Blenheim w ing tank
with only one hit in five; during the Battle only
one or tw o of the eight guns w ere normally
loaded wi th thi s am munition. Other 0303in
and 792mm incendiaries were only half as
effective. Sim ilarly, w hile both German and
British steel-cored armour-piercing (AP) rounds
could penetrate up to 12mm of armour plate if
fired directly at it from 200yd, most of the bul lets w ere deflected or tumbled by first passing
through the fuselage skin or structure. In consequence, only a quarter to a third of the bullets
reached the Blenh eim 's 4m m -thick armour
plate at all, and very few penetrated it.
The Luftwaffe relied more on their 20mm MGFF cannon, w hich had som e interesting advantages and disadvantages. The guns w ere more
than twi ce as heavy as the 792mm MG 17 and
fired only half as fast, about 9 r.p.s. The muzzle
velocity was also low er, giving a di fferent trajectory and time-to-target. Moreover, the 60round capacity o f its drum magazine limited the
w eapon to only about 7sec of firing. However,
the big shells w eighed about 12 times as much
as the RCMG bullets, and their high-explosive
filling caused blast damage, as well as throwing
high-velocity shell frag ments around.
In May 1940 the Bf I 09E-4 entered service w ith
the modified MG-FFM gun, adapted to fire the
new Minengeschoss (mine shell) am munition
w hich had very thin wa lls and a doubled capacity for high-expl osive (HE) and/ or incendi ary.
As a bonus the shells were lighter, permitting a
higher muzzle velocity. The theory w as that solid
bullets or AP cannon shells reli ed on hitting the
relatively small vital areas to have an effect,
w hereas an HE shell could cause serious damage regardless of where it struck . There is no
doubt that this theory was correct: the Spitfires
AEROPLANE, SE PTEM BER 2004

and Hurricanes would have had far m ore effect

on the Luftwaffe's bombers had they been armed
w ith four MG-FFM cannon, w hich would have
weighed little more than their battery of RCMGs.

ABOVE The Messerschmitt

Bf 109E-4 's modified MGFFM gun could fire Minengeschoss ammunition.

THE SEARCH FOR BIGGER GUNS

BELOW Even the 12 O303in

Browning machine-guns of
the Hurricane II often
lacked sufficient pun ch to
do decisive damage.

The RAF had realised years before the war that

the 0303in MG might become inadequate as a
pri mary aircraft gun, given the steady increase
in speed, strength and toughness of aircraft. They
considered, but rejected, O'SOin (12' 7mm) guns
as giving insufficient advantage over the 0303in .
Instead, they sought a good 20mm cannon,
w hich they thought would be far more effective
due to its explosive am munition, and found one
in the new French Hispano-Sui za HS A 04. This
was selected in the late I 930s, and specifications w ere w ritten for a new fighter to carry it
(the Westland Whi rl wind), but problems in setting up UK factories meant that only a few guns
w ere available for the Battle of Britain .
To save time the Hispano was fitted to existing
single-engined fighters for testing, and a squadron of Spitfire IBs saw service during the Battle.
How ever, the gun was designed to be mounted

59

AIRCRAFT ARMAMENT

"Throughout the Hispano cannon's life, fine-tuning of insta II

ABOVE AWestland

Whirlwind has its four

nose-mounted 20mm
Hispano cannon serviced.
The drum-shaped objects
are the belt feeds.
ABOVE RIGHT,TOP Reloading
the nose MG 1S1/20 of a
JGS4 Bf 109F. Ease of access
was a great asset.
ABOVE RIGHT, BOTTOM Four
wingmounted 20mm
Hispano cannon made the
Hurricane IIC a formidable
opponent.

BELOW The Hispano cannon

installation in a Spitfire
wing. The change from
drum magazine to belt feed
greatly increased
ammunition capacity.

60

on a massive engine block, and did not like being

installed in a fa r more flexible w ing. Moreover,
the initia l installation had the guns on their sides
to bury the big drum magazines in th e w ings,
and the Hispano did not like this at all. The
result was such appall ing unreliability, the guns
frequently jamming after only one shot, th at the
squadron requested its old aeroplanes back.
Throughout th e Hispano's li fe, fin e-tuning of
installations w as required to make it reliable in
w ing mountin gs. Guns mou nted in the much
more rigid fuselages of such aircraft as the Whirlw ind, Beaufighter and Mosquito caused far fewer
probl ems. Once working properly, the big ca nnon w as a formidable weapon. compared w ith
the MG-FF it was slightly faster-firing at 10 r.p.s.,
and its much bigger cartri dge cases generated a
considerably higher mu zzl e veloci ty, w hich
improved both hit probability and penetration .
While th e Alli es never introduced the Minen geschoss technology, so their shells only carried half the HE/ Incendi ary (HEI) load, the heavy
Hispano shells' better penetration m ean t they
could in flict considerable damage. The Hispano
soon changed from a eo-round drum magazine
to a belt feed giving much greater ammunition
capacity (w hich the MG-FF never had, other than
in an obscure nightfighter installation). The penalty was that th e Hispano was almost tw ice as
long and double the we ight of th e German gun;
un welcome features for Wing-mounted weapons.
RAF fighters carried a mi xture of HE or HEI
and plain steel "ball" (prac tice) rounds (w hich
had good penetrati on) until the emergence of
the semi-armour piercing incendiary (SAPI) in
1942, after wh ich th e standard loading was
50/ 50 HEI and SAPI. The German ca nnon were
not exclusively loaded w ith Minengeschoss, but
used th em mi xed with older-typ e HEI-T shells
(retained because, unlike th e M-Geschoss, th ey
could carry a tracer) and later some API round s
as well, in varying proportions.
The Germans were not satisfied w ith th e MG-

FFM, w hich had been adopted as an interim

measure pending a purpose-designed ca nnon.
This duly emerged as th e Mauser MG 151 , w hich
gradually took over from 1941 . Initially, th e Mauser had been designed to use a high -velocity
15mm cartridge, but it saw relati vely little service in this form . Wartime experience led to th e
ca rtridge case being mod ified to accept the
20mm shells fro m the MG-FFM , surre ndering
muzzle velocity and penetration in th e in terests
of far greater destru ctive effect. The 15mm version w as available with HE shells, but they w ere
considered too small. The resulting MG 151 / 20
w as in termediate in size, w eight and mu zzle
veloci ty between th e MG-FFM and the Hispano,
but was faster-fi ring at 12 r.p .s. It was a superb
design w hich the Americans tri ed to copy, producing some 300 guns in 060in (15mm) cali bre,
designated T I 7, but th ey never adopted it.
Later in the war, various new German guns
emerged w ith calibres of up to 50mm . The most
signi ficant ones were the Rhei nmetall -Borsig
MG 131 , MK 103 and MK 108. The MG 131 w as
a 13m m HMG in tended to replace the RCMGs in
both fix ed and movable mountin gs, and th erefore kept as small and light as possibl e, making
it the least pow erful HMG to see service. The
other guns were both in 30mm calibre but otherwise very di fferent. The MK 103 was a huge,
high-velocity slow- firing gun, w hile th e MK 108
fired much smaller, low -velocity cartridges at a
very creditable 10 r.p .s., and was only hal f th e
size and w eight. Their use was really prompted
by the difficulty the Luftwaffe was experiencing
in shooting down USAAF B- 17 bombers. Their
30m m M-Geschoss HEI shells were highly
effective, containing four tim es as much HE as
the 20mm version, and three or four hits with
these could bring down a bomber, compared
w ith 20 hits with 20mm am munition.
In 194 1 th e USSR was drawn into th e w ar. As
w ell as the very-fast-firing (30 r.p.s.) 762m m
ShKAS, it had in service an excellent HMG, the
AE RO PLANE, SEPTEM BER 20 04

AIRCRAFT ARMAMENT

llations was required to make it reliable in wing mountings"

12 7mm Universal Berezin, and a 20mm cannon,

the ShVAK. The ShVAK had actually started life
as a 127mm gun. It w eighed the same as the
MG 151 / 20 and was slightly faster-firing, but
the ammunition was less effective as the shells
had only a small HE capacity. Towards the end
of the w ar the Berezin was also altered to fire
the same 20mm ammunition as the ShVAK; at
2Skg the resultin g B-20 w as the lightest gun o f
this calibre to see service . The Soviet preference was to install all guns in the fuselage of
their little fighters rather than in the wings, to
concentrate firepow er and m ake the aircraft
more agile. Because this limited the number of
guns, a relatively small number of aircraft was
equipped w ith larger guns as engine cannon,
including the powerful 23mm VYa-23 and 37mm
NS-3 7. Because of the weight, recoil and relatively low rate of fire of these w eapons, these
we re deemed suitable for expert pilots only.

ENTER THE AMERICANS - &THE JAPANESE

The end of 1941 also saw America and Japan
enter the wa r. Th eir aircraft weapons we re very
different. Am erica relied almost entirely on the
Brownin g m achin e-gun , not just in OSOin
(12'7mm) calibre, but, for the first couple of years,
in 030in (762mm) as we ll. The Japanese army
and navy air forces follow ed their own paths, the
army steadily up-gunning from 77mm through
127mm machine-guns and later 20mm cannon, with 30mm and even larger guns seeing
limited service by the end of the war. The navy
started with a mixture of 77mm MGs and Type
99 20mm cannon and continued to rely on this
cannon, although it did make some use of
HMGs and was also introducing 30mm guns by
the end of the wa r. As in Germany, the destruction of American heavy bombers w as a strong
incentive for the development of w eapon s of
30mm or larger calibre.
The Americans did not intend to make such a
commitment to the Browning MGs. Both before
AERO PLANE, SE PTEM BE R 2004

and during the war considerable efforts we re

made to secure alterna tive aircraft guns. Tria ls
of foreign equipment resulted in the selection
of the 20mm Hispano-Suiza HS.404, large numbers being made. The Browning-designed 37mm
M4 cannon w as also introduced, although used
almost exclusively by the Bell P-39 and P-63.
How ever, the standard fighter armament became a battery of six O'SOin Browning M2 HMGs.
This has led to the often-expressed view that
the O'SOin M2 was the best all-round fighter
gun of the w ar. After all, the USAAF and US
Navy fighters unquesti onably came to dominate
the skies in w hich they fought. If th ere had been
a better gun, America would have used it.
How ever, the truth is not quite as simple as
that. There are tw o issues here; how good was
the O'SOin M2 compared w ith other HMGs, and
how effective w as it compared w ith cannon?
The most obvious comparator was the Sovi et
UB, which fired ammunition of virtually identi cal pow er. The UB weighed 2Skg , compared w ith
the M2's 29kg, but the Soviet gun fired at 175
r.p .s., compared with around 13 for the M2. In
terms of power-to-weight ratio the Berez in was
therefore clearly superior. The Bro wnin g fared
better against most other HMGs, as they all fired
less-p ow erful ammunition, so the M2 enjoyed
advantages in range and penetration. How ever,
it had a slightly lower rate of fire th an the German and Japanese guns (both around I S r.p .s.),
and w as also bi gger and heavi er. The most
powerful of all of the HMGs was the I Smm MG
151, but this was heavi er and slower- firing than
the M2. Overall, therefore, the O'SOin M2 was
not the best of the HMGs but was about average, w ith reasonable performance for its we ight.
How did HMGs compare w ith 20mm ca nnon?
The first problem is that the cannon varied
hugely in size, we ight and performance. The MGFFM , Type 99- 1 and B-20 we re all lighter than
the M2, but the first tw o we re significantly worse
in terms of muzzle velocity and rate of fire, al-

ABOVE Ade Havilland

Mosquito Mk VI fighterbomber provides a graphic
illustration of its firepower
during a night-time firing
of the four 20mm cannon
and four O303in machineguns installed in its nose.
This was the most widely
used of all the Mosquito
fighter variants.

61

AIRCRAFT ARMAMENT
RIGHT AFocke-Wulf Fw
190A-S/Ull shows off its
underslung 30mm
Rheinmetall-Borsig MK 103
slow-firing gun.
FAR RIGHT The Soviet Union's
Yakovlev Yak-9 was armed
with a 20mm ShVAK engine
cannon and a single
127mm UBS heavy
machine-gun.

ABOVE The French HispanoSuiza HS.404 cannon, with

a 60-round drum magazine.
BElOW Three sectioned 20 x
80mm cartridges for the
German MG-FFM, showing
the HE-T (left) and the
high-capacity M-Geschoss
shell (centre). On the right
is an API.

62

though the B-20 matched the M2's rate o f fire

and was not far behind in velocity. The Japanese Ho-5, Type 99-2 , ShVAK and MG 151 / 20
we re all somewhat heavi er. Muzzle velocities
and rates of fire were closer to the M2's but generally still not as good. The Hispano wa s significa ntly heavi er and slo we r- fi rin g until th e
British Mk V emerged near the war's end, matching th e MG 15 1120 in w eight and rate of fire.
The foregoing compares only the guns' effi ciency ; it takes no account of ammunition, the
area in w hich the HMG loses most ground. The
20mm cannon shells were not only tw o to three
times heavier than HMG bull ets, but their HEl
conten ts greatly increased their effective ness.
Although HE ammunition was avail able for
most HMGs, their small bullets severely limited
the quantity of chemica ls ca rried, so the Ameri cans decided not to use them . Initially, the M2
used a mi x of incendiary and AP bullets, w ith
some tracers, but in 1944 the MS API began to
take over. Rather curiously, this was based on
the Sovi et B.32 API used in the Berezin.
It is di ffi cult to assess the effectiveness of different ammunition types, but various tests suggest that a typical World Wa r TWo-era HE or
incendia ry shell, w ith chemical contents form ing about 10 per cent of total shell we ight, was
about twice as destructive as a plain steel shell
o f similar size and we ight. This makes it clear
that 20mm ca nnon we re considerably more destructive for a given total w eight of arma ment
than any HMG could hope to be. For exampl e,

the 050in MS API contained less than one gram

of incendiary, whereas the 20mm Hispano SAPI
achieved similar armour penetration but carried more than ten times as much incendiary.
This advantage was recognised by the US Navy.
After comparing the 050i n M2 and the 20mm
Hispano they estimated that the cannon was
three tim es as effective . In other words, the typ ical RAF arm ament of four 20mm ca nnon was
twice as destructive as the USAAF's six 050in
HMGs, for very little more we ight. Propone nts
of the Browning HMG point to its excellent ballistics, whi ch enhanced its ran ge and hit proba biit y. But the Hispano's muzzle velocity wa s
very similar, and although the blunt-n osed shells
were less aerodynamic the difference over
typical air-combat ranges was not significant.
Data on the principal aircraft guns is shown
in the table below. Of the RCMGs, only the
0303in Browning has been included, most o f
the others being very similar in effectiveness.
The cannon's advantages are clearly shown
in the decisions made as a result of comba t
experience by air forces w ith a choice of good
HMGs and cannon. We have already seen how
Germany preferred th e 20mm version of the MG
l SI despite its poorer ballistics. In the 127mm
Berezin the Soviets had arguably the best HMG
of the w ar, but they still preferred the heavi er,
slower-firing 20mm ShVAK. Japan had several
good HMGs available; the army's Ho- I 03, and
the navy's 13mm Type 3, a 050in Browning
chambered for slightly larger-calibre arnrn uni-

Principal aircraft guns compared

Gun

Calibre

0303in
7'7x56
MG 131
13x64
Ho 103
12-7x81
127 Breda 12'7x81
0'50in M2 12'7x99
127 Berezin 127xl08
MG 151
15x96
Type 99-1 20x72
MG-FFM
20x80
MG 151120 20x82
20x94
Ho 5
ShVAK
20x99
Type 99-2 20xl01
Hispano II 20xll0
Hispano V 20xl10
VYa-23
23x152
MK 108
30x90
MK 103
30x184
37mm M4 37x145

Bullet
Muzzle Rate of Weight of Destruct. Gun
Gun
Weight g Vel m/sec Fire r.p.s. Fire Kg/sec Effect
Weight Efficiency
11
34
33
33
43
48
57
128
92
92
79
95
128
130
130
200
330
330
608

750
750
770
770
890
840
960
600
700
800
730
790
750
860
830
900
505
860
610

20
15
15
12
13
17
12
8
9
12
14
13
8
10
125
9

10
7
25

022
051
050
040
056
082
068
102
083
11 0
110
123
102
13
1-62
180
33
23
152

20
48
45
36
60
97
94
108
126
192
154
143
120
200
250
234
580
693
160

10
17
23
29
29
25
42
24
28
42
37
42
35
50
42
68
60
141
96

20
28
20
12
21
39
22
45
45
46
42
34
34
40
60
34
97
49
1-7

NB 1. The "Destructive Effect"

column produces an approximate indication of the firepower rating of the gun,
calculated by multiplying four
factors: projectile weight,
muzzle velocity, rate of fire,
and a multiplier for the
average percentage content
of incendiary or HE material
(5% content =xt -s,
10% =x2, 20% =x3).
2. The "Gun Efficiency"
column is calculated by
dividing the "Destructive
Effect" by the "Gun Weight".
3. Guns which were
synchronised to fire through
the propeller disc would have
their rates of fire reduced by
between 10% and 40% from
those shown

AEROPLAN E, SEPTEMB ER 2004

AIRCRAFT ARMAMENT

LEFT Acomparative photo

of the ammunition for the
principal WW2 fighter
guns. From left to right:
British 0303in (NxS6mm
- representative of all
RCMG cartridges); American O'SOin M2 (l 207x99);
French/British/American
20mm Hispano (20x11 0);
Soviet 1207mm UB
(1207xl08) and 20mm
ShVAK (20x99); German
13mm MG 131 (13x64),
lSmm MG 151 (1Sx96),
20mm MG-FFM (20x80),
20mm MG 151/20 (20x82),
30mm MK 108 (30x90) and
30mm MK 103 (30x184);
Italian/Japanese 127mm
Breda-SAFATIH0-103
(l207x81); Japanese 20mm
Type 99-1 (20x72),20mm
Type 99-2 (20xl0l) and
20mm Ho-S (20x94).
FAR LEFT The six O'SOin
Browning M2 heavy
machine-guns for the North
American P-Sl Mustang.

-,

tion , but they made increasing use of cannon.

So why did the Americans not make more use
of cannon, speci fically the 20mm Hispano they
already had in mass producti on? There w ere
tw o main reasons. One was certainly that the
M2 w as adequate for its purpose. In Western
Europe the main adversaries w ere fighters,
which w ere much easier to damage and shoot
dow n than bombers. In the Pacific Theatre the
Japanese aircraft were initi ally poorly protected
and easy to shoot down. Later Japanese aircraft
were better protected, but again these were
usually fighters. If the Americans had faced the
need to stop raids by heavy, well-protected
bombers, it is likely that the HMG's shortcomings would have been starkly revealed.
There was another reason, how ever, w hich
explains why the US Navy, despite rating the
cannon very highly and facing the need to deal
with attacking bombers and kamikazes, fitted it
to few aircraft. That was serious production problems with the American Hispano, which gave i t
a repu tation for unreliability. Despite production running well into six figures, the American
Hispano failed to achieve an acceptable reliabil ity standard for the duration of th e war.
To return to the original question , were the
America ns right to rely so heavily on the 050in
M2 w hen all other combatant nations had a
clear preference for cannon of at least 20mm
calibre? The answer has to be yes. It w as adequate for its purpose, and was the only satisfactory aircraft gun in producti on in the USA. It

was very reli able (except w here the installations created problems), was made in huge
quantities, and the simplification of supply by
comparison with the diversity of weapons used
by the Axis powers gave a major logistical advantage. However, the Ameri cans could get away
w ith using a weapon so deficient in destru ctive
power not only because of the nature of their
opposition, but also because the size and engine
power of their fighters enabled them to carry a
battery of at least six guns, thus makin g up in
quantity what they lacked in destructive quality.
The advantages of the 20mm Hispano M2 were
not entirely ignored. It was ca rried by Lockheed
P-38s, together w ith four 050in Brownings. It
was also installed in nightfighters, which needed maximum firepow er to convert a short firing
opportunity into a kill. Four were installed in
Northrop's P-6 1 Black Widow, and two could be
mounted in a Grumman F6F-5N. The cannon's
extra fi repower was also appreciated for
ground strafing.
After the war the US Navy quickly changed
over to the 20mm cannon in its improved.
faster-firing and more reliable M3 form, but
the USAF stayed with the 050 M3 until the
fighting in Korea demonstrated once and for
all that the HMG had had i ts day. From the
mid- 1950s the USAF at last replaced the old
Browning with 20mm cannon, initially the M39
revolver and then the M6 1 rotary - just as
most of the rest of the w orld was moving D
up to 30mm !
~

Anthony Williams is the

co-author, with Emmanuel
Gustin, of Flying Guns:
World War 2 - the
Development of Aircraft
Guns, Ammunition and
Installations 1933-1945,
published by Airlife in 2003
and distributed by The
Crowood Press. His web
address is http://www.quarry.nildram.co.uk

BELOW Comparative
drawings of the principal
Second World War fighter
guns, to approximately the
same scale.

"So why did the Americans not make more use of cannon, specifically the
20mm Hispano already in production? There were two main reasons"
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201Tm Ho-5

.50 8rown~ M2

qj-- - .

ih

12.7mm UnNerul Beruln

O8fWl.on FF wCll arum

2(lmm SWAK

! I

20mm Type 99-2

(MQ.FF and IJN

Type99-1~J

30mm MK 108

30mm MI( t03

AE RO PLANE, SEPTEMBER 2004

63