This weapon is a short-rifled howitzer without a recoil or counter-recoil system, mounted on a
light aluminum alloy carriage. A funneled (Venturi) tube is attached to the rear of the bored
breechblock; its function is to allow the gases to disperse to the rear, thus eliminating a
recoil mechanism. The firing mechanism is seated in a cone-shaped receptacle and centered in
the breechblock by vertical struts. The weight of the complete gun is reduced to a minimum
by using hollow machined parts, plastic washers, tubular carriage, and aluminum alloy
body. Because of the weight of the complete piece, it lends itself to use by airborne troops.
The general characteristics of the gun are:
|Date of manufacture|| ||1942|
| Complete||325 lbs|
| Barrel||98 lbs|
| Carriage||63 lbs|
| Wheels and axles||36 lbs|
| Breechblock and Venturi tube ||66 lbs|
| Breech ring||62 lbs|
|Length of gun (over-all)||45 in|
|Length of barrel||29 1/2 in|
|Rifling||28 lands and grooves -|
uniform right-hand twist;
one turn in 19 calibers
|Maximum range**||3-4,000 yds|
|Rate of fire**||12-15 rpm|
|Sights**||Cross-leveling gear, and|
straight tube telescope
|Ammunition**||HE and hollow charge|
|Carriage||Platform or tripod type;|
detachable wheels for transport
|Tactical use||AT and antipersonnel|
The tube is of monobloc steel construction. On the breech end, interrupted collars provide
for attachment of the tube to the breech rings. It is also machined to seat the extractor
and the barrel lock. Externally and midway on the barrel, a steel band is clamped. Its
purpose is to lock the barrel and the front leg of the tripod in transport.
b. Breech Ring
This part of the gun is recessed to receive the barrel and breechblock. It contains borings
for the extractor pin, breech-lever mechanism, "safe and fire" lever as well as the barrel
lock. The trunnions for mounting it to the carriage and the elevating rack are also attached
to the breech ring.
The breech is of the horizontal sliding block type. It is bored to receive the firing housing
and firing lever. The firing housing, which acts as a diffuser for gases escaping to the rear, is
screwed at the rear to secure the funnel-shaped "Venturi" tube. The breech mechanism lever
performs a double function. It operates the breechblock and also cocks the piece when the
lever is depressed.
d. Venturi Tube
This funnel-shaped tube is screwed on to the rear of the breechblock. Its purpose is to
disperse the gases to the rear, eliminating recoil.
The top carriage or body is constructed of an aluminum alloy, formed with a circular base. It
contains borings for the elevating and traversing mechanisms and lock, as well as the trunnion
caps for seating the trunnions. The gun can be traversed 360° by locking the elevating
mechanism, but its ordinary traverse is 60°. Elevation is limited to 42° by stops, but
the rack can be locked at 20°. At the right side is a bracket for attaching a small
f. Lower Carriage or Platform
The lower carriage consists of the wheels, platform, three tubular legs, tubular guide rails, tubular
axletree, base ring traversing rack, and stub axles.
The wheels are light-weight metal disks fitted with solid rubber tires and can be quickly
detached from the axletree.
The three tripod legs are pivoted in lugs on the base ring. The front leg can be placed in one of
two positions for firing by engaging it in a slot in the center of the axletree. The left and right
legs can be placed in two positions by locking them in slots of the guide rail. The three tripod
legs have small spades for steadying the gun while firing.
Remarks: The method of firing the piece and the types of cartridges, propellants, and
projectiles are, and will be, unknown until they are secured. Many theories have been suggested
by observers, but until the projectile is received and fired it remains pure conjecture. No detailed
information is available at present concerning the sighting equipment, because the captured weapon
arrived in the U.S. without sights of any kind. There is a sight bracket attached to the left side
of the carriage.
*Extracted from a recent Aberdeen Proving Ground report.
**From a British report.