Then of course their was extra craziness like the Char, Matilda, and KV-1 which were pretty much impervious to 50mm guns too.
The 50mm gun really didn't have much higher penetration then the 37mm in the first place, though it suffered considerably less loss of its merger performance with range. Needed tungsten shells to be a serious defense against the T-34. But the problem with the Char B1, Matilda and KV-1 was that all of them were very slow, and just as importantly had very short cruising radiuses on one tank of fuel. This made it very hard to actually get the vehicle into action, much of its fuel would be consumed on the approach march and assembling the attack. The Tiger 1 had the same problem. The T-34 had speed and driving range which were good by any standard, and it was that balance that counted. The Matilda though did do very well climbing hills, which you cannot say about most heavy tanks of its time.
The KV-1 was pretty forward thinking as far as pre war heavy tanks went at the time though. The Char was pretty shit, a post World War 1 Frankenstein with a bizarre layout.
The layout was bizarre, but it was intended to have a major role breaching fortifications. Its also essentially a 1934 design updated through 1937, and by 1940 had several replacement projects running. It did have a lot of ammunition which was a big plus for its intended assault role. If you think about it zig zagging across the battlefield, shelling different bunkers in turn, while the 47mm turret fights off enemy counter attacks it makes a certain amount of sense.
The KV-1 is 15 metric tons heavier than any of those western European tanks, so you’d hope it would be a lot better. In fact it was too heavy for its engine, and later versions had less armor to weigh less and have more mobility. Basic KV-1 was 47 metric tons, against 26 for a Matilda and 32 for a Char B1bis. KV-1S went down to 42.5 tons. Interestingly this is also about how much an early T-72 weighed thirty one years later.
The Matilda was born of a flawed doctrine and was frequently SOL even when encountering really light AT guns because the British didn't manufacture HE rounds for the 2pdr. (Which may not have been completely unjustified, as I heard somewhere that the 40mm round of the 2pdr wouldn't produce a lot of fragmentation anyway. Supposedly less than a hand grenade. Don't quote me on that though.) I think Skimmer told me Matildas frequently had to just run over AT guns they encountered.
Everyone using 37mm guns produced HE for them, and wanted it. The shells aren’t that effective one for one, but you could carry a vast number of them and fire as rapidly as the loader can move. You didn’t expect shot kills kill with these small guns against anything. They would indeed crush anti tank guns when they could, but all tanks were known to do this, it’s a good way to ruin them. I don’t know that I ever said anything about it before though; it’s not an uncommon topic in armor warfare that they make stuff go squish.
One problem with Matilda is it just doesn’t have that much ammunition, despite being designed for infantry support, though it’s not a small amount either. 93 rounds of 2pdr, and 2,800 machine gun rounds. A Char B1bis had 74 rounds 75mm, 50 rouns 47mm and 9,600 machine gun rounds. KV-1 had 90 rounds of 76.2mm and 3,024 machine guns rounds. The KV-1S restowed the tank and packed in 114 shells and the same amount of MG ammo. Ammo and fuel count for a lot when your vehicle is slow, withdrawing from combat to rearm can take considerable time, and it takes twenty shells on a good day to score a tank kill even for famously effective stuff like the 88mm flak guns.
At least the frontal area in France was small enough for the Germans to deal with the Mattie and Char by rolling up the nearest AA or Artillery battalion. In Russia where the frontal area was *massive* and dirt tracks much less paved roads are few and far between, defensive vehicles like the KV-1 could get away with a lot more.
Yes, the Germans had no depth in the east. It was common for the frontline to consist only of a single line of infantry positions, with only fortified artillery batteries and command posts behind it. So it was pretty easy for a T-34 attack to break past a few 37mm guns and then run amok. The Russians also became very good at infiltrating infantry between the lines, often in very large units and then just collapsing the Germans defenses. The Germans saving grace was they just had much better command and control and training at the operational level, and could use what Panzer and mobile anti tank guns were available to isolate the Russian tank hoards and defeat them in detail.