GMC T68 - 40mm Gun Motor Carriage.1942

[klem]

Designed in 1942 by the American Ordnance Company, an old-established gun-making concern of Bridgeport, Connecticut, the M3 half-track carrier, known as the 40mm Gun Motor Carriage T68 (GMC T68) and featured unusual gun layout. The guns were placed, one above the other, a configuration with an overhead equilibrator cylinder. In June 1943 the only copy of the GMC T68 was tested by the Antiaircraft Artillery Board, without success which ended this experience.(The Bofors Gun-Terry Gander)

 

[ImportantSimone5]

Designed in 1942 by the American Ordnance Company, an old-established gun-making concern of Bridgeport, Connecticut, the M3 half-track carrier, known as the 40mm Gun Motor Carriage T68 (GMC T68) and featured unusual gun layout. The guns were placed, one above the other, a configuration with an overhead equilibrator cylinder. In June 1943 the only copy of the GMC T68 was tested by the Antiaircraft Artillery Board, without success which ended this experience.(The Bofors Gun-Terry Gander)

It looks very strange.

 

[JWilly]

If you want to minimize dispersion-causing mount flex due to recoil force and vibration, don't mount the guns on substantially long levers extending away from the structural frame.

If you want to maximize vehicle stability when driving and when emplaced and firing, mount the guns as low as possible so that the vertical distance from the ground to the center of mass is as small a fraction of the vehicle ground-contact width as can be achieved.

 

[Maxrobot1]

I imagine that getting the 40mm Bofors clips fed would be difficult.

 

[JWilly]

In the early days of US Bofors adoption, there was talk in USA of re-designing the gun to normally be mounted on its side so that shell entry would be from the side with ejection from the opposite side, and to accept belt fed ammo...akin to the British Vickers pom-pom family with the same caliber. My guess is that the prototype shown above, if it had been better received, might have been re-designed for the next prototype to have the guns mounted and fed that way, once such guns existed, of course.

We think that side-by-side guns are "natural"' akin to the M42 and similar designs, but in fact an over-under design would be more sensible for side-fed, belt-fed guns.

Perhaps a bit of hubris on the part of American Ordnance Company. Certainly not the first time that American designers have assumed that weapons and vehicles designed outside USA must be inferior and would benefit from an American re-design.

 

[Scott Kenny]

In the early days of US Bofors adoption, there was talk in USA of re-designing the gun to normally be mounted on its side so that shell entry would be from the side with ejection from the opposite side, and to accept belt fed ammo...akin to the British Vickers pom-pom family with the same caliber. My guess is that the prototype shown above, if it had been better received, might have been re-designed for the next prototype to have the guns mounted and fed that way, once such guns existed, of course.

We think that side-by-side guns are "natural"' akin to the M42 and similar designs, but in fact an over-under design would be more sensible for side-fed, belt-fed guns.

Adding a belt feed would have been a great improvement to the Bofors 40mm L60. It would have allowed much fewer crew per gun tub.

Perhaps a bit of hubris on the part of American Ordnance Company. Certainly not the first time that American designers have assumed that weapons and vehicles designed outside USA must be inferior and would benefit from an American re-design.

Considering that Ordnance Branch went through one set of blueprints and changed dimensions from (example) 5"-0.010" to 4.95" +-0.005" JUST TO CHANGE TO PLUS OR MINUS, I can't argue with that. Note that the weapons made to the changed prints did not function at all.