Sights
Several different sights were used with these guns. One, the Telescopic Sight Type E-5, was a unit power (no magnification) optical sight that fitted inside the horizontal tubular magazine. It had a crosshair reticle that appeared to be at the same distance as the target, and thus all the gunner had to do was to position the cross hairs with respect to the target. This sight appears to have been favored by the AAF, since it most closely resembled the aiming picture seen when using a reflector sight. In general, gunners using this sight prefered to stand fairly close to the eyepiece in order to get the greatest field of view. While the optical sight was simpler to use and afforded more eye freedom than the iron sights, it lacked “speed rings” that could assist in estimating lead. Alternatively, AAF guns might be equipped with the B-10 ring sight.
NAMES: Telescopic gun sight
DESCRIPTION: The Army type E-5 telelscopic gun sight is used with .30 and .50 caliber M2 machine guns.
The sight is a telescope of approximately one power, incorporating a set of removable cross hairs.
It is non-compensating, but when used with a type C-4 adjustable mount, it has limited adjusting
facilities for aligning the line of sight to the bore axis of the gun.
Dust caps, connected by a leather strap, are provided to keep the lenses from being scratched.
CHARACTERISTICS:
Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . .approximately 9½ by 1¼ by 1¼ inches
Weight . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .approximately 3/8 pound
RELATIONSHIP OF PARTS: Used with:
Army type C-4 flexible gun sight mount, A. E. Reference Number 53-3400, on .30 or .50 caliber M2
machine guns.
ARMY
A. E. REFERENCE NUMBER: 52-5350
SPECIFICATIONS:
Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93-24667
Superseded:. . . . . . . . . . . . . . . . . . . . . . . . . . . . 24667
MANUFACTURERS: International Register Company, Buhl Optical Company.
A. A. F. DRAWING NUMBER: 40B7830
TYPE DESIGNATION: E-5
A. S. C. stock number: 5200729700
PRODUCTION STATUS: Not under procurement for initial installation.
SHIPPING DATA: Shipped as a complete unit.
NAVY :
There is no Navy equivalent for the Army item.
NAMES: Flexible gun ring sight
Gun ring sight
Ring sight
.30 caliber gun ring sight
DESCRIPTION: The type B-10 flexible gun ring sight is used on flexibly mounted .30 caliber M2 machine
guns. It is usually employed with an A-4 flexible gun post sight.
The gun ring sight is made of rust-proof steel which is given a dull finish to prevent reflection. It
consists of two concentric rings and an adjustable clamp. The larger ring is connected to a metal post
mounted on the clamp. The smaller ring, or center peep, is supported from the larger ring, and contains
two cross hairs which are used to align the bead on the post sight with the target. The clamp,consisting
of a horizontal bar with two hooked lugs, secures the sight to the cover plate of the machine gun.
When in position, the ring sight will be approximately eight inches from the gunner’s eye.
CHARACTERISTICS:
Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .approximately 3½ by 23/8 by 7/8 inches
Weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . approximately ¼ pound
Large ring (inside diameter). . . . . . . . . . . . . . . . . . . . . . . .approximately 2¼ inches
Small ring (inside diameter). . . . . . . . . . . . . . . . . . . . . . . .approximatley 7/32 inch
RELATIONSHIP OF PARTS: Used with:
Army type A-4 flexible gun post sight, A. E. Reference Number 52-4600 on a .30 caliber M2 machine
gun, A. E. Reference Number 93-1520.
ARMY
A. E. REFERENCE NUMBER: 52-4900
SPECIFICATIONS:
Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93-24587
A. A. F. DRAWING NUMBER: 37B3574
TYPE DESIGNATION: B-10
A. S. C. STOCK NUMBER: Refer to chart.
PRODUCTION STATUS: Under procurement.
SHIPPING DATA: Shipped as a complete unit.
NAVY
TYPE DESIGNATION: B-10
BU. ORD. DRAWING NUMBER: 297061
AVIATION ORDNANCE STOCK LIST NUMBER: 2-S-3106
ORDNANCE PAMPHLET NUMBER: 263 and 865
PROCUREMENT STATUS: Under procurement.
MODELS BELOW ARE INTERCHANGEABLE
Models are used in services as noted in column 4
A-Army, N-Navy, B-British
Most Navy guns, on the other hand, were equipped with iron ring and bead sights, with the ring mounted atop the horizontal magazine tube and the bead near the muzzle. Proper use of ring sights require that the eye be positioned at the correct distance from the ring. This distance is called the base distance. Standard base distances for Navy flexible aircraft gunsights were 13, 16 and 20 inches. The sights mounted at the forward end of the magazine on the MacGlashan guns had a 13-inch base distance, and the user was encouraged to position his eye as close as possible to the gun grips in order to achieve this distance. Sights mounted at the rear of the magazine had a 16-inch base distance, and therefore the gunner stood back from the gun somewhat.
Other than being just plain fun to use, the main virtue of the air machine gun was that it taught the novice gunner that he could not aim directly at a moving target but had to offset his point of aim and continuously move his gun if he was to obtain hits. It also provided a gentle introduction to machine guns, since it was quieter and had a minimum recoil.
Accessories
MacGlashan made several accessories for its guns. The first, and probably the most popular, was a stand for the gun. This consisted of a vertical tube mounted on a U-shaped strip steel base that was designed for compatibilty with wooden decking. A smaller inner tube telescoped within the main upright and could be secured at any desired height. At the top of the inner tube was a clevis into which the the gun’s receiver fitted. A bracket was attached to the upright post to hold the power pack. This mount was found more frequently at Navy ranges, while the AAF tended to mount its guns on sturdy vertical iron pipes.
The second accessory was a counter control unit, or rounds counter. This unit, which could be used in place of the power pack, limited the number of shots that could be fired before resetting, and could be set from one to 40. It’s intent was to teach the student to conserve ammunition, encourage burst control, and, incidentally, to reduce barrel wear.
A final item was a target stand that provided two moving airplane models at the ends of a rotating arm. No mention has been found of the use of this device in the literature.