background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html

M113-based Mortar Carriers, Part 1, 

Revised April 26, 2002 

 
 

Picture 1: 
Some time 
ago, Cesar 
de los 
Bueis 
from 
Spain sent 
us some 
interesting 
images of 
a vehicle 
he had 
spotted 
and 
photographed. 
Known to 
him as the 
M113 
TOA 
120mm 
Mortar 
Carrier, I 
thought it 

was about time for us to take a closer look at this particular vehicle. I also thought it might be interesting 
to compare it to M113-based mortar carriers used in the USA over the past few years, including the M125 
81mm Mortar Carrier, the M106 107mm Mortar Carrier, and the M1064 120mm Mortar Carrier. We will 
first explore the Spanish 120mm carrier in Part 1, and then in Part 2 we'll take a quick look inside the 
three main US carrier vehicles.  
 
The basic chassis for this Spanish vehicle is a FMC M113A1 and it has the typical driver's equipment at 
the front left corner of the hull. It also has the engine installed to the right of the driver, a rear cargo 
compartment with stowage bins along the side sponsons, and an internal fuel tank on the left-rear 
sponson, all customary for the M113A1. The changes made inside this vehicle to convert it to the Spanish 
mortar carrier version are centered around a Spanish-produced ECIA 120mm Mortar System, consisting 
of a cannon assembly, bipod assembly, and baseplate. The weapon can be fired from inside the vehicle as 
there is a pivot base mounted directly to the floor panels. Of course, the upper cargo compartment doors 
must be opened during operation. Since we already have a comprehensive web page in AFV INTERIORS 
about the basic M113, we will spend most of our time in these two pages comparing the interior of this 
vehicle with the mortar carriers used by the US Army during the past few years.  
 
 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html (1 di 6)25/05/2007 16.47.17

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html

Picture 2: 
From outside 
the Spanish 
120mm 
mortar 
carrier you 
can clearly 
see the 
characteristic 
lines of the 
simple 
aluminum 
box hull of 
the FMC 
M113 
design. Up 
on top are 
the open 
commander 

and driver's access hatches, the commander's hatch ring mounting a flexible .50cal Browning HB 
Machine Gun. Notice that there are no external fuel tanks on the rear of the hull, one of a number of 
indications that this vehicle is based on the M113A1 when the fuel tank was still located inside the cargo 
compartment, not on an A2 or later vehicle.  
 
 

Picture 3: 
The first 
thing I 
noticed 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html (2 di 6)25/05/2007 16.47.17

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html

when 
looking at 
this image 
of the 
interior of 
the rear 
compartment 
is that this 
ECIA 
120mm 
mortar has a 
completely 
different 
base setup 
than any I 
have seen 
inside a 
M113 

mortar carrier before, certainly different than the US M106A1 (107mm), M125A1 (81mm), and M1064 
120mm Mortar Carriers. In all the US M113-based mortar carriers, the mortar tube is mounted on a fully 
rotating turntable and can theoretically traverse to fire in any direction. The 120mm mortar tube setup 
seen in this Spanish vehicle does not have that ability. It is mounted in such a way that the mortar 
traverses through a limited arc, approximately 70 degrees, and only when the weapon is pointed toward 
the rear. You can clearly see where the bottom of the forked tube support runs along a track that arcs 
gently across the floor. You can also see that the lower end of the mortar tube is attached to ball socket on 
a tunnel support (that runs across the floor from sponson to sponson), again different than all the US 
carrier platforms I am familiar with. It is clear that the stowage along the both sidewalls is also different 
here, the ammo stored vertically and horizontally in different locations and in different bin designs than 
on the US vehicles.  
 
 

Picture 4: 
A closer view of the left side of the hull interior 
shows the ammo storage on the side wall of the 
Spanish hull next to the 120mm mortar tube (the 
tube is also called a "cannon" on occasion). The 
tube support tunnel that runs from side to side is 
clearer in this image. On the left hull wall are 
vertical ammo storage tubes bolted to the floor 
next to the fuel cell (that sits up on the sponson). 
You can also just barely see a number of 
horizontal ammo storage tubes on the left 
sponson, forward of the fuel cell. Further 
forward are some shelves with webbing straps 
and then further forward still are the driver's 
controls. The mortar crew apparently carry 
assault rifles inside the vehicle, the weapons 
appearing to be Spanish CETME Modelo L 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html (3 di 6)25/05/2007 16.47.17

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html

assault rifles.  
 
At the upper right is the commander's seat and 
seat support rising from the floor to the ceiling, 
the same setup as seen in most M113 series 
vehicles. The seat allows the commander to ride 
low in the hull under armor using periscopes to 
view the surroundings, or high, with his head out 
of his over-head hatch. Down below the mortar 
is an equipment box with the vehicle track 
number 143.  

 
About those assault rifles.... After WWII, the core of the Mauser team which designed the German 
Sturmgewehr 44 went to work for the Spanish CETME (Centro de Estudios Tecnios de Materials 
Especiales) and developed a new assault rifle based on its original layout. The resulting weapon was made 
of low-grade steel and was built with the emphasis on cheapness and reliability rather than good looks. 
The Spanish army adopted the resulting CETME B, or 58, as its standard rifle in 1958, the weapon 
chambered for a unique light 7.62mm round. In 1964, Spain decided to adopt the more powerful 7.62mm 
NATO cartridge and CETME modified their rifle design to make the Modelo 58 C. The most recent 
version of the rifle was first produced in 1984 to use the NATO 5.56mm round, and that CETME Model 
L is what we see here (thanks Javier Hueso and Gorka L. Martinez Mezo).  
 
 

Picture 5: 
This shot of the driver's compartment in the 
Spanish vehicle is pretty much stock M113A1, 
with the steering tillers in front of his seat, the 
periscopes over his head around his roof hatch, 
and his primary instrument panel to the left of 
the driver, angled slightly for improved viewing. 
The shelves to our immediate left are usually 
reserved for radios, but I can see only an 
intercom connect box here, the radios have been 
moved over to the other side of the hull, out of 
our sight. Again, you might want to compare 
this photo with others in the M113 web page in 
AFV INTERIORS to see what minor 
differences you can find between the vehicles.  

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html (4 di 6)25/05/2007 16.47.17

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html

 
 

Picture 6: 
Here is the 
view of the 
right side of 
the Spanish 
hull interior. 
The upper 
shelves are 
filled with 
radio gear 
and the lower 
ones are 
empty right 
now, with the 
exception of 
a "bone 
dome" 
helmet. 
Further 
forward is 
another 

armored vehicle crew helmet, hanging from the rear engine compartment access hatch. Notice that the 
typical warning signs about carbon monoxide poisoning are in the same place as in the US vehicles, but 
now they are in Spanish. Down to the lower right of the access hatch is the large black duct for the crew 
heater, again the same as in US vehicles. The white dome light on the ceiling is the same, and even the 
radio gear looks familiar to me, although I am no expert on modern vehicle radios. One of our readers, 
Mr. Alastair Bowie, wrote to reminded me that the set is either an AN/VRC 160 (with AN/PRC 77) or 
AN/VRC 125 (with AN/PRC 25). Both sets are externally just about identical, except the ID plate. By the 
way, the AN/PRC 77 is being replaced by the PR4G family of radios but still survives in second line 
units. All Spanish first line units have converted to the digital PR4G family of vehicular sets (thanks again 
Al and Gorka for your help here).  
 
 

Picture 7: 
Stepping 
back down 
the lowered 
rear ramp 
we once 
again have 
an excellent 
overall view 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html (5 di 6)25/05/2007 16.47.17

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html

of the 
Spanish 
120mm 
mortar 
carrier 
compartment 
and mortar. 
The forked 
support 
brace for the 
tube can be 
adjusted to 

elevate or depress the weapon, the mechanism to do this seen directly in front of us. This forked support 
brace is also used on a portable base which is normally hung on the side of the hull, so the tube probably 
releases from its pivot on the tunnel support so it can be removed from the vehicle and set up 
independently. The support tubing is very similar to the design used on the US M1064 120mm Mortar 
Carrier, except this one has the support legs bent into angles to fit the track on the floor, and the US 
support legs are straight. Again, notice how massive the tunnel support appears in this photo, especially 
how the ends are bolted to the side hull sponsons with cast plates and numerous bolts.  
 
The cargo doors are open over-head and provide more than enough clearance for the limited rear traverse 
of the big mortar. Having to open up an armored vehicle in order to fire its main weapon like this is one of 
the main drawbacks of using the M113 as a mortar carrier. When used like this, the crew is very exposed 
when setting up and firing the mortar, for the crew is exposed not only to over-head shell bursts, but also 
to any NBC contamination. Some countries (those with deep enough pockets) are gradually converting 
their open mechanized mortar carriers to enclosed and turreted types for this reason. One example of the 
newer enclosed type that comes to mind is United Defense's 120mm Armored Mortar System (AMS) 
120mm mortar turret, which can be mounted on a number of different chassis. But there are others now 
available and currently in trials.  
 
That concludes Part 1. In Part 2 we will take a look inside the three American vehicles based on the M113 
that have been used over the past few years, and compare them to this Spanish version.  
 
 

TO M113 MORTAR CARRIERS PART 2

 

BACK TO AFV INTERIORS HOME PAGE

 

(c) 2002, 2003 AFV INTERIORS Web Magazine 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa1.html (6 di 6)25/05/2007 16.47.17

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html

M113 Mortar Carriers, Part 2, Revised 

April 26, 2002 

 
 

Picture 1: 
This is the 
second part 
of a two-part 
series on 
M113-based 
mortar 
carriers. In 
Part 1 we 
looked inside 
a modern 
Spanish 
carrier with a 
120mm 
mortar, and 
now, for 
comparison, 
we will 
briefly 
explore the 
three M113-
based carriers 
that have 
been used by 
the US over 
the past few 
years.  
 
This is a US 
Army photo 
of the view 
inside a US 
M125A2 
with its 
81mm M29 

Mortar installed. Notice the fully rotating turntable on the floor with the mortar elevated on a 
platform that is centered on the turntable. The elevated platform was necessary because the mortar 
tube was short and the platform ensured the blast from firing the mortar was directed completely 
outside the vehicle. Notice that the roof hatches over the mortar are now circular instead of 
rectangular as seen on the various versions of the basic M113.  

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html (1 di 9)25/05/2007 16.47.18

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html

 
As I mentioned, the mortar used in the M125 series of vehicles was the well-known and trusted 
81mm M29, with roots going all the way back to the French and WWI, but best known when used by 
the US Army as the 81mm Mortar M1. As the M1, the 81mm Mortar tube weighed only 44lbs and 
was less than four feet long. While muzzle velocity was only 700ft/sec, it could lob rounds over a 
mile and a half, at the rate of 18 to 30 per minute, depending on the crew and local conditions. With a 
few minor modifications, including beefing up the tube from low to medium pressure, the M1 Mortar 
was renamed the M29 Mortar in the late 1950's. As carried inside the M125 Mortar Carrier, the M29 
Mortar could be dismounted and deployed away from the vehicle using a portable base plate that you 
can see here stowed on the roof to the left of the commander's cupola.  
 
There were stowage bins for 114 mortar bombs and fuzes carried inside and, as you can see, a .50cal 
Browning M2 HB was also mounted on the commander's cupola ring. Over the past twenty years or 
so the US Army has been in the process of converted these vehicles to the 120mm Mortar Carrier 
M1064, or other similar configurations, and to the best of my knowledge this has now been 
completed. There are very few, if any, M125 81mm Mortar Carriers in the US inventory now, but at 
one time it was a dedicated part of many armor and infantry unit assets.  
 
 

Picture 2: 
This is the interior 
stowage drawing for 
the M125A2 carrying 
the 81mm M29 
Mortar. Beginning at 
the left rear, you can 
see a fuze rack located 
next to the fuel cell (in 
its typical position up 
above the left track). 
Further forward on the 
left track sponson is a 
vertical stowage rack 
for ready round 
mortar bombs, and 
further forward still is 
the large battery box 
with a radio rack shelf 
above. Mounted next 
to the battery box and 
radios is a crew seat, 
and a similar seat is 
seen across the 
vehicle on the 
opposite side.  
 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html (2 di 9)25/05/2007 16.47.18

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html

The crew heater occupies this forward right corner of the track while further back from the second 
crew seat along this side are two more bins for mortar bombs, this time the bombs stowed 
horizontally. Typically, at the time the M125A2 was in use, mortar bombs were stowed in their own 
protective tubes, and the black tubes would be seen lying on these shelves when the vehicle was fully 
stowed and ready for action.  
 
 

Picture 3: 
Also 
recently 
phased out 
of US 
Army 
service is 
the M30 
107mm 
(4.2inch) 
mortar. 
Most of 
these 
weapons 
were 
removed 
from 
active and 
reserve 
units 
during the 
1980s, in 
favor of 
the NATO 
standard 
M120 
120mm 
Mortar. 
However, 
the old 
M30 
107mm 
mortar can 
still be 
found in 
some 
NATO 

countries. This is the M113-based carrier for the mortar, known as the M106 series of Mortar 
Carriers. Like the M125 Carrier with the 81mm mortar, the M106 Carrier had to stop first in order to 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html (3 di 9)25/05/2007 16.47.18

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html

setup before the weapon could be fired from inside the carrier. Like most other mortars that were 
mounted inside US carriers, the 107mm mortar could be dismounted from the M125 carrier and used 
away from the vehicle. In this case, the large base plate is stowed hanging on the left side of the 
vehicle hull; only part of it is visible at the far left.  
 
Known to many who used it as the 4.2in (more about this later), the M30 107mm mortar was 
designed a bit differently from others in the US inventory, in that it had a rifled tube which stabilized 
the bomb by spinning it rapidly while in flight. Again, notice that the weapon is mounted on a fully 
rotating turntable, similar in design to the one used in the M125, although the tube support is quite 
different in appearance, consisting of a single tube while the support for the 81mm M29 mortar is 
forked.  
 
 

Picture 4: 
And here we 
have the interior 
storage sketch 
from the manual 
for the M106A2 
Mortar Carrier 
with the 4.2in 
(107mm) inside. 
The original 
M106A1 was 
first produced in 
September of 
1964 and for 
many years was 
the standard 
Mortar Carrier 
for the US 
Army. The 
interior setup is 
similar in some 
respects to what 
we saw in the 
M125A2. Again, 
beginning at the 
left-rear, there is 
a fuze rack next 

to the fuel cell, but now there is also a rifle rack next to the fuze rack. Further forward from the fuel 
cell on the sponson is the same vertical ready round storage rack we saw previously, and further yet 
along the sponson is the battery box with radio rack above and crew seat along side.  
 
Another crew seat is across the isle next to the crew heater, and then there are two bins with shelves 
again for mortar bomb storage, very similar in most respects to the interior arrangement of the 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html (4 di 9)25/05/2007 16.47.18

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html

M125A2. Both vehicles also have the commander's seat support post and seat in the typical location 
toward the front of the fighting compartment so he is located directly under his cupola.  
 
The US M30 4.2in Mortar (also known as the "four-deuce") originated as the M2 Chemical Mortar 
and was first designed to fire white phosphorus, smoke, Lewisite (an organic arsenic gas compound), 
choking gas, mustard gas, and two types of tear gas back in the days of the Great War. In 1951 it was 
modified slightly and renamed the M30 4.2in Mortar, officially only later becoming the M30 107mm 
Mortar in order to conform with standard NATO criteria. As the M30 107mm Mortar, the weapon 
was said to have elevation limits of 45 to 85 degrees with a traverse of 16 degrees without having to 
move the base. The most common bombs in use at this time were high explosive, white phosphorus, 
chemical, and illuminating, with a range of around 3.5 miles. Rate of sustained fire was said to be 
around 20 to 25 rounds per minute, with a muzzle velocity of around 960 ft/sec.  
 
 

Picture 5: 
And finally, this 
is the current US 
M1064A3 
Mortar Carrier 
with its 120mm 
M121 mortar 
(also known as 
the Battalion 
Mortar System-- 
BMS), the 
mortar looking 
suspiciously like 
an Israeli 
120mm Soltam 
mortar. Not only 
does this vehicle 
have the two 
rear external 
fuel tanks, but it 
is also fitted 
with the RISE 
powerpack 
(275hp Detroit 

Diesel 6V53T turbocharged diesel engine driving through an Allison X200-4 cross-drive 
transmission).  
 
Also, you may have noticed that unlike the Spanish vehicle in Part 1, the US 120mm Mortar Carrier 
still uses a fully rotating turntable. The M1064A3 vehicle has the same general silhouette as the 
M113A3 personnel carrier, but there are structural differences, including a welded-in cross beam, 
additional floor support structures to withstand mortar reaction forces, and an enlarged three-piece 
over-head firing hatch. And although the 120mm weapon seems to have a 90 degree traverse 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html (5 di 9)25/05/2007 16.47.18

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html

potential on the turntable, the vehicle still has to be positioned so the mortar is fired to the rear. 
Typically, all the M1064s have a four-man crew and a total of 69 mortar bombs stowed onboard.  
 
 

Picture 6: 
The stowage 
diagram from the 
manual shows how 
this interior is very 
different than the 
two earlier 
designed M113-
based vehicles we 
have seen. Since 
the fuel cells are 
now outside, there 
is more room for 
ammo storage 
inside. A large 
shelved bin at the 
left-rear corner of 
the compartment 
takes the place of 
the fuel cell, and 
further forward is a 
revised rack for the 
fuzes. The battery 
box is in the same 
location in the A3, 
and the typical 
location for the 

radio shelf is still above the battery box. Crew seats are again next to the battery box and also across 
the isle, but now there is a rifle rack mounted directly behind the commander's seat, partially 
obscuring his position when you look into the vehicle from the open ramp. On the right side of the 
hull are additional horizontal storage racks for additional bombs while a second fuze rack takes the 
remaining space at the right rear.  
 
Lockheed Martin Ordnance Systems was selected in 1988 as the primary contractor for R&D and 
initial production of the US 120mm mortar and ammunition. Lockheed Martin teamed with Soltam 
Limited of Israel (thus the similarity in appearance of the two 120mm systems) for the design. 
Subsequently, the U.S. Army awarded Watervliet Arsenal the primary contract for weapon 
production under the Arsenal Act competition, along with Martin Marietta. Approximately 1,190 of 
the earlier M1064 carriers were to be converted to the M121 BMS systems (M1064A3) and the same 
number of M121 Mortars were to be produced, for a total cost of around 108 million dollars. 
Conversion of the earlier vehicles ran to June of 1998, and production of the M121 Mortars ended in 
October of 1996.  

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html (6 di 9)25/05/2007 16.47.18

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html

 
Current enhancements to the system include an improved sight unit, improved smoke round, 
conventional and infrared illumination rounds, a full-range training round, and the M30 mortar 
ballistic computer. Proposed long-term enhancements include extended range precision guided 
munitions and a digital fire control system; a few of the guided munitions are currently under test and 
could provide some very interesting options for the mortar system.  
 
 

Picture 7: 
Another US Army 
photo of a M1064A3 
120mm Mortar Carrier 
compares the relative 
size of the vehicle and 
a typical 120mm 
round to the size of the 
crew members. It is 
hard to believe that 
any crew would want 
to be inside this thing 
when the huge mortar 
is fired, the blast 
effects on surrounding 
troops are world 
famous. The mortar, 
especially when fired 
inside the carrier, 
produces a blast 
overpressure (impulse 
noise level) in excess 
of allowable limits. 
Crew members that 
are subjected to this 

blast overpressure must wear properly fitted E-A-R brand disposable earplugs, and soldiers in the 
immediate vicinity of the mortar firing (within 200 meters) must have properly fitted hearing 
protection. When firing in the carrier-mounted mode, a Blast Attenuation Device (BAD) is attached 
to the muzzle of the M298 cannon to reduce the blast effects on the mortar crew. You can see this 
device in this photo as well as others, the device is the funnel-shaped addition at the end of the mortar 
tube.  
 
According to the US Army's published Basis Of Issue Plan (BOIP), provisions are made inside the 
M1064A3 for three M16A2 rifles, a sight extension, and an extractor rod directly to the rear of the 
commander's platform seat. Other modifications beyond the A2 version include improved driver 
controls, a shock-mounted driver's seat, collapsible driver's footrest, and mounting provisions for a 
bolt-on armor kit. The vehicle complements other battalion organic weapon systems by transporting 
the mortar in order to provide a high rate of high angle support to engage defilade targets and fill in 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html (7 di 9)25/05/2007 16.47.18

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html

areas of dead space for direct fire weapons. As I mentioned, the M1064A3 Carrier is currently 
replacing the earlier versions on a one to one basis, primarily in Armored and Mechanized Infantry 
Battalions (six or four each), Armored Cavalry Squadrons (three per troop) and in Motorized Infantry 
Battalions (six each). Typically, the crew consists of a squad leader, gunner, assistant gunner, and 
ammo bearer/operator/driver.  
 
 

Picture 8: 
Our final image illustrates the US 120mm 
mortar, designated as the M121 when carrier 
borne, and M120 when towed. Range with 
current munitions is approximately 7,240m and 
rate of fire, depending on crew, is stated to be 
16 rounds/min for the first minute and then four 
rounds/min sustained. Weight of the mortar, 
support and base is 319lbs and ammunition now 
consists of high explosive, smoke, illumination 
(visible light and infrared), and full-range 
practice. A Mortar Fire Control System (MFCS) 
is currently in development for coordinating fire 
missions and should be available in the near 
future. When towed behind a M998 HMMWV, 
the mortar is transported on its own M1100 
trailer and a five man crew is required. 
Elevation is from 710 to 1510 mils (40 to 85 

degrees) while deflection is approximately 272 mils total, right to left. Each turn of the traversing 
handwheel equals approximately 5 mils.  
 
The major components consist of the M298 Cannon, which is a smooth bore type with a crew 
removable base cap. When fired from a M1064 Mortar Carrier, a Blast Attenuator Assembly is 
mounted on the muzzle end as we saw earlier. Weight of the tube alone is 110lbs (50 kg). The mortar 
mount is either the M190 or M191 Mortar Mount, allowing cross-leveling, traversing, and elevating 
adjustments. The M190 has straight legs (as you see here) and the M191 has removable leg 
extensions to allow mounting in the M1064 Mortar Carrier. The mortar mount is equipped with a 
buffer mechanism and traversing extension. Weight of the M191 is 78lbs (35.5 kg). The sight being 
adjusted here is a M67 Sight Unit, which includes a mount assembly and a 4X elbow telescope with 
radioactive tritium used to illuminate scales, indices, level vials, and reticle. Weight of the sight is 
2.25lbs (1.02 kg). 120mm smoothbore mortars are also used by France, Germany, Denmark, and 
other allied armies. The Russian-developed counterpart is the M43 120mm mortar, which has a range 
of 5,700m, weighs roughly 600lbs, and has a six-man crew. All of them are roughly equivalent in 
firepower, although western designs have advanced ammunition research ongoing.  
 
And that concludes our brief exploration of a special Spanish Army 120mm Mortar Carrier and the 
various modern US M113-based mortar carrier vehicles used over the past 20 years. My thanks again 
go to Cesar de los Bueis from Spain for the use of his interior photos of the Spanish Army vehicle. 
Thanks also to Javier Hueso, Alastair Bowie, and Gorka L. Martinez Mezo for their comments, which 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html (8 di 9)25/05/2007 16.47.18

background image

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AFV%20Interiors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html

greatly improved the pages. The other illustrations used in these two web pages are mainly FMC or 
US Army photographs and diagrams, coming either from their publicity packets or directly from the 
operator's manuals in my own library.  
 
 

TO M113 MORTAR CARRIERS PART 1

 

BACK TO AFV INTERIORS HOME PAGE

 

(c) 2002, 2003 AFV INTERIORS Web Magazine 

file:///H|/Modellismo/AFV%20Interiors/[armor]%20-%20AF...iors/afvinteriors.hobbyvista.com/m113toa/m113toa2.html (9 di 9)25/05/2007 16.47.18


Document Outline