SU-76M Assault Gun: The Second Most Produced Soviet Armored Vehicle of WWII

Today we're looking at the SU-76M. The State Defence Committee by about mid-1942 wanted a self-propelled platform that could operate in support of the infantry and the mechanised forces. There were three platforms that were put up. So the Goiki Automobile Plant came up with three prototypes. The GAZ-71, which was a 76.2mm anti-tank gun. The GAZ-72, which was your 37mm anti-aircraft variant. And your GAZ-73, which was a 45mm tank destroyer variant. We start getting into plant number 38 and 40 coming into the fold here. Plant 38 come up with what was called the SU-12, which was the predecessor before this. It was determined that those other three platforms, scrapped them, were run with the SU-12. So from December 1942, they made 26, including the original prototypes. From February of 43, those platforms went for training. So from training, then we go into about May of 1943, where the SU-12 was then accepted into service as the SU-76. This vehicle was the second most mass-produced vehicle compared to the T-34. So in the SU-76 variant, there was about 608, 609, if you include that prototype. And in the SU-76M, we now go to 12,698. So there's some changes along the way with this vehicle. This particular vehicle, as we look at the hull complete, was modelled off the T-70B. As opposed to the T-70 itself, we've added an extra road wheel. So we've lengthened this hull. Torsion bar suspension. Now I've driven this vehicle a few times. The only issue that I've found with it is if this track is not tight, it has a habit of jumping off the front sprocket here. How do you tension the track on this, Joe? Pretty easy on this one. Grab yourself a tool. Unlock this nut here. This is on a spline. And then we grab a bar, which is generally curved. Stick it in here. And depending on which side you're working on, you'll either push down or you'll lift up to tighten the track. And then get your other crew member to wind that back in and lock it into position. So very easy to do. If we look at T-70, we had an engine on this side and the far side. To get the transmissions synchronised was quite difficult. Early on, the crews referred to this vehicle as the Suchka because of the two engines either side, where the transmissions really had to be synchronised. And if they weren't, it made it really hard to steer. Vehicle number 328 onwards. The gas factory go back to the drawing board. They get rid of the engine on this side. And now we have two engines in tandem, joined one behind each other on the right-hand side. Both the gas 203 six-cylinder petrol engines give about 85 horsepower each. Compel this vehicle along at about 50 kilometres an hour. So not too bad. The gearbox that we can see in here is that of a ZIS 5 truck. So this is a four-speed transmission. Because it's a H pattern, the gears are very close together. So it can take a bit of practice to actually get it into the right gear. The drive's not too bad. Got two steering tillers here. The only thing I found with this is the hatch opening mechanism here actually fails with the left-hand tiller. So when you pull them back, you've actually got to watch your hand as you're steering to the left. So when we go from T-70, which has about 35 millimetres on the frontal armour, this goes down to reduce weight. Most sources say around 25 millimetres. Put the old calipers on this one, and we're getting sort of, that was about 28. Some areas we can get to close to 27, others are 26. So we'll go on an average that it's anywhere between 25 mil to sort of that 26 mil. We slope it back at 60 degrees, that'll give us a line of sight at about 50 millimetres. So when we get to here, the side of the vehicle, we're doing about 16 millimetres. When we get to the casemate, on this side we're looking about 10 millimetres. On the front here, this is about 25 millimetres. So an inch on the front, which is not too bad. The first couple of hundred vehicles didn't have a roof. Then when we get past those 300 vehicles, we go into having a six millimetre roof on top. Later on, they took this roof out because they said it was to reduce weight with inside the cabin. We didn't have a roof, we had a roof, we didn't have a roof. And then there was a Lieutenant Colonel out in the field who said we need protection for these soldiers because of plunging fire. So he recommended we have a number of sections of plate. So within its short time frame of 42 to 45, it went through about four different modifications of having a roof or no roof. We have about 15 millimetres of armour on the back, so it's quite thick. But the actual door is only 10 millimetres of armour. But you'll see a lot of photos between the SU-76s where they will have a split fold door and then a panel here that will lower as well. And if we look at some later SU-76s from about here, they will taper down. So there's no armour protection there. But if you look at some of the photos from Factory 40, they have this extra bit of armour that comes all the way around. This is the 76.2mm ZIS-3 gun, so the divisional gun. And the modifications that were made to it went up to a ZIS-8 gun. Within the fighting compartment, we can hold 60 rounds. So up the front here, hold a 29 mixture of AP and HE. We've got another rack here where we put HE. Got another rack where they generally said that they put the high velocity ammunition. Down here, which was missing at the moment, should be another rack of 10. The position I'm in here is the commander's position. He would have his sight that would pop up above the top of the casemate here that he can look out of. This radio system started off being the R-12, which was an infantry type of radio. But even back during World War II, these had a lot of valves in it, other than like today, where we use a lot of electronics. But when the gun fired, those valves would break, so the radios become useless. So they swapped it to an R-9 radio, which is in the T-34. This variant, even though it's called the P-113, I believe this is a Polish variant, but it looks very similar to the radio that should be fitted within this vehicle. And they had intercommunication system between the commander and the driver. This position here is the gunner, and behind him is the loader. Now, his sighting system is standard for a artillery piece. This vehicle has essentially three different roles. We can use it as an assault gun, so we're supporting the infantry. We can use it as a self-propelled gun, so we can use it as an artillery piece, firing I think anywhere up to about 15 to 17 kilometres using HE. Or we can use it in the anti-tank role. The sighting system is not designed for it to be shooting at tanks, and especially if the tank is moving, they just can't lay on. But if they come across any sort of armoured vehicle, they would stop their primary role and go into the anti-tank role. And being a small vehicle coming in at I think about 10.8 tonne, had a very low ground pressure of about 7.6 psi. So it allowed this vehicle to go across those sort of boggy, marshy areas quite successfully without getting bogged. They have a DT machine gun that they can stow in this position here. Those racks that you can see hold the magazines for the DT machine gun. Now, they provided these vision blocks for the DT machine gun, so it'd sit on a pintle and look out, so it can do either side. The only problem was you had a very narrow field of view. So this can actually go to negative five degrees in elevation and about plus 15, and we can go to I think it's about 37 degrees left and right. So it is quite a versatile gun. So for a four-man crew, I think these vehicles actually would have performed the job fairly well. Yes, it's a runner. So if you'd like to go for a ride on this vehicle, check out the link below, and we'll see you at AusArmourFest 2024.