T3 HMC (75/37) - Yo Dawg, I Heard You Like Cannons

[Would you like to see this in-game?]
  • Yes
  • No
0 voters

TL;DR: An experimental version of the T3 HMC with a 37mm cannon mounted on top of the 75mm howitzer.

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Note: This is the only picture I could find of this tank. If you have any other significant information, please let me know.

History:

The need to motorize artillery was felt by the US military as early as WWI. Many projects attempted to satisfy this need, however, most ended in rejection. The T3 HMC is one such rejection, which was based on the lessons learned from the T1 HMC, a HMC based on the T1 Cunningham. At the time of the T3 HMC’s development, the US had finally begun mass tank production. One of the tanks produced en masse was the M1 Combat Car, a lightweight and incredibly quick tracked vehicle. These characteristics made the vehicle very appealing to engineers as a possible platform for a mobile artillery piece. In 1939, construction of a pilot vehicle was approved and the T3 HMC was born. This vehicle featured a the M1A1 75mm pack howitzer as its main weapon, mounted on the right side of the fighting compartment, while a turret equipped with a .30cal MG occupied the left. Only two men could fit in the small SPG. This resulted in very odd crew roles. The driver was responsible for aiming and firing the weapon and the commander was responsible for loading, while also being in control of the MG turret. These roles made firing on the move incredibly difficult. The vehicle went through trials at Aberdeen before being shipped over to Fort Bragg where it underwent more testing. One of these tests involved the the mounting of a M1916 37mm cannon to the top of the howitzer just to see if the driver could aim it. Of course, these tests didn’t yield good results and the 37mm was dismounted. The T3 HMC project was later abandoned due to being unsuitable for any role.

Place In War Thunder:

Quick derp vehicles have always had their fair share of fans. Multi-gun vehicles have always had their fair share of fans. What happens when you combine the two vehicle types? You get the T3 HMC (75/37), a vehicle equipped with two very different cannons, both of which are very limited in use. You need to be at close range to effectively use the 75 and you might as well be shooting peas with the 37. That being said, usefulness isn’t the only thing that matters. Vehicles that are simply just dumb fun are also necessary. Playstyle would be rather unique due to its unique armament. Your speed would easily allow you to get close enough to use your howitzer and your 37 could act as a support weapon, quickly pelting whatever is in front of you. Due to its uniqueness, I think that the best implementation for this vehicle is as a low tier GE premium or event vehicle. It was an incredibly experimental variation of an already experimental vehicle. It has no place in the tech tree.

Specifications:

Armament: M1A1 75mm howitzer, M1916 37mm cannon, and 1x .30 cal MG

Dimensions: 4.14m, 2.40m, 2.26m (L,W,H)

Weight: 10430kg

Armor: 16mm max

Crew: 2

Ammunition: 75mm: HEAT and HE 37mm: HE and LE

Speed: 72kph

Horsepower: 250hp

Sources:

Tank Archives: T18 HMC: Quick Howitzer

Off The Mark: US Revamp: T3 HMC

M1 combat car - Wikipedia

https://www.ibiblio.org/hyperwar/USA/ref/FM/PDFs/FM23-75.pdf

M116 howitzer - Wikipedia

Stuart: A History of the American Light Tank Vol. 1 by R.P. Hunnicutt

3 Likes

I don’t know how useful this information is, but the same 37mm M1916 in your photo (with the same mount as well) was used as a training weapon, allowing soldiers to simulate the firing of larger guns without wasting the respective ammunition. Perhaps it served a similar function on the T3?


37mmsubcaliber

2 Likes

I’m pretty sure this is only meant for sub-calibre training. It’s in the 75mm manuals.

Edit: Here.

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Actually, have you considered that it could instead be a spotting gun? A smaller caliber weapon fired first to gauge the range before zeroing in with the larger cannon.

It would make sense for this to be the focal point of a test or two on such an early HMC.

Doubtful, even the 75mm howitzer manual has a sub-calibre section.

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It’s specifically a training weapon and not taken into combat, these were very common in the US.

Right, but we’re talking about a test vehicle here, it would not make sense to install a training device on it. The mount for the M1916 is also noticeably different to production versions, and along with the title photo clearly reading “TEST”, I don’t think this is for the typical reasons you would install a subcaliber gun.

1 Like





Different types of sub-calibre mounts are incredibly common but their purposes are all the same. It’s for training.

3 Likes

Funny enough they came back as anti-infantry and urban warfare kit. Some of these could be good mods for USA with infantry mode on the way even if that was not the idea of them we can still put them to good use. Might stop a guy with a RPG about to slash your tank.
7ih0Ssy

None of these were ever intended for combat though. These were training devices to well, be a bit austere on ammunition costs. A machine gun bullet is cheaper than a shell, and a 37mm shell is cheaper than a 75mm one.

1 Like

True but I think the M10 & M17 sub-caliber mounts could be argued even if they have 50 round belt I think it would be a handy unlock with infantry mode on its way.

And for the other as long as a semi useful round could be fired it could be a nice to have addition for just the use of keeping future infantry away from your vehicle.

37mm is so far out, must be a headache to reach for the loader

+1 since it is pretty funky.

2 Likes

2 min reload also if there is a smoke round for the 37 could be a nice.

There isn’t a smoke round sadly.

It only has one non-training round, “HE Mk.II”, which is a SAPHE shell that ended up with the worst of both worlds. The filler is pretty light and the penetration is only about 8 mm @ 10 m in-game. Since its SAP, it’s going to overpen unarmored trucks unlike standard HE.


When you factor in the long reload due to it being located outside the tank, it would be practically useless to the point a regular co-ax mg would be preferable.

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I’m flipping my vote to -1 since its just a bit of training kit with no actual utility.

1 Like

Maybe it can be a modification to the T3 hmc? Tho I feel like it will be incredibly buggy for some reason.

2 Likes

Theoretically, but at that point, there are many sub-caliber training mounts to be added. It just seems odd to me for many tanks you’d meet in battle to be be running gun training modifications in order min-max their tank’s firepower.