The DS-39 is an air-cooled heavy machine gun designed by Degtyarev, which was intended to replace the 1910 Maxim as the standard Soviet HMG. It was lighter and more mobile than the Maxim, and also offered two rates of fire for ground and anti-aircraft use. Testing all seemed to go well, and production began in 1939. The guns first saw field service in the Winter War with Finland, and there they showed serious problems – see my previous video on the DS-39 history and mechanics ics for all the details. They were taken out of production, and the Maxim would go on serving until the Goryunov SG-43 was developed a few years later. Today, I have the fantastic opportunity to take this DS-39 out to the range! So let’s see what those two rates of fire are really like…
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That’s much more compact than I’ve always pictured those things… For some reason, I’ve always thought these were more like the DShK in size than they really are.
Cool gun, though.
How to fix a stoppage on a Soviet HMG: hit it with a hammer.
Indeed percussive maintenance might look like matching Soviet technology but mallets were often used by British WW1 at their Vickers machine guns, according to
http://www.theaerodrome.com/forum/showpost.php?s=8a4fd259d7106244824d49d327f76478&p=162778&postcount=5
A major contributor to synchronisation problems (and gun reliability generally) was ammunition quality, which tended to be variable during the War. Pilots frequently carried a mallet with which to hammer the loading lever in order to chamber a recalcitrant cartridge. In an attempt to resolve this, the British introduced in 1917 “Green Label” (or “Green Cross”) .303 in ball ammunition specifically for synchronised guns. This was taken from standard production lines, but carefully selected from batches which complied with tighter manufacturing tolerances and gave reliable ignition. This proved successful and was followed up in 1918 by establishing special production lines to make high quality ammunition for this purpose. This was known as “Red Label” (also as “Special for RAF, Red Label”, “Special for RAF” and finally “Special”) and ball, AP and SPG tracer ammunition were produced
Everyone used (or still uses) mallets with their Maxim (or Vickers) guns. And it is not wrong to have a mallet close by, when shooting machine guns, because when they heat up they all can get sticky covers from the metal expanding. More modern designs do not stick as much, but it can still happen.
“So let’s see what those two rates of fire are really like…(…)”
Beware that if it is Lahti-improved version it might give different Rate-of-Fire than original DS-39 https://www.jaegerplatoon.net/MG2.htm
Finnish troops captured bit under 200 machineguns of this type (most of them in 1941) during Continuation War. Also Finnish troops soon noticed the reliability problems these weapons. Aimo Lahti studied captured DS-39 machinegun and in year 1942 he planned it 8 improvements, which considerably reduced the problem. Maybe the most important improvement was decelerator switch, which was added to the weapon’s bolt, as the original high rate-of-fire had proved related to reliability problems. Other improvements included making gas-piston thinner (otherwise it typically jam the weapon after only 1,000 shots or so) and adding chamber for soot in end of gas-piston (otherwise the soot could jam gas-piston after some 4,000 – 5,000 shots). Holes of gas-regulator were also increased in size to allow more gas getting to gas-piston and angle of contact piece was changed. In addition also firing pin was thinned. The last but not least of improvements was modifying the weapon’s feeding system so that Finnish 200-round metal ammunition belts M/32 could be used. While these Finnish improvements reduced reliability problems of DS-39 in some extent, they failed solving the basic problem – the feeding system of this machinegun had been poorly designed and it simply didn’t work well. Late 1942 Finnish military withdraw all captured DS-39 machineguns from the troops and sent them to VKT (Valtion Kivääritehdas = State Rifle Factory), where this 8-part improvement plan was implemented. After making these improvements the machineguns were re-issued to Finnish frontline troops. While not part of the improvement plan Finnish military removed the attachment of optical sight from the captured DS-39 (it seems that the optical sights belonging to these weapons were not captured – at least not in real numbers). Finnish soldiers also usually removed the weapon’s shield, as the protection it offered was highly questionable. Year 1943 Finnish Army typically issued either 20 250-round fabric belts or 25 200-round steel belts with each DS-39 machinegun. In its highest the number of DS-39 in Finnish use peaked to 175 and after 2nd World War 145 of them still remained. During Continuation War Finnish frontline troops used these machineguns. After World War 2 the remaining DS-39 were warehoused until being declared obsolete year 1986 and mainly scrapped. Nowadays unknown number of Finnish-captured DS-39 machineguns remains in Finnish military museums and collections of Finnish collectors.
Note that mentioned optics was supposed to be default equipment, as according to http://armedman.ru/strelkovoe-vooruzhenie/1937-1945-strelkovoe-vooruzhenie/stankovyiy-pulemet-degtyaryova-ds-39.html
Расчет пулемета состоял из 4 человек, в комплект каждого пулемета входило 2 ствола, 12 коробок с лентами, оптический прицел.
i.e. Crew numbered 4 humans, kit issued with each machine gun contained 2 barrels, 12 boxes for belts, optical sight.
thus shield (generally not used by Finns) feature hole to allow said sight usage, see photos and manuals https://forum.guns.ru/forum_light_message/36/1322887.html
Basic parameters of said optical sight: objective diameter 12 mm ocular diameter 22 mm magnification x2,0 Field of View 20°
These sights, like the constitution of the USSR, existed only on paper.
And “paper tolerates everything.” (C)
My granddad was a machinist and was in the habit of carrying a small pipe wrench in his back pocket. If something mechanical was reluctant or showing signs of distress, he’d pull out the wrench and whack the item in question “Just to show it who was in charge”. It worked a remarkable number of times and made me a believer.
I once actually threatened a belt-sander with scrapping if it didn’t start up. You can guess the rest of the conversation.
A recalcitrant CZ rifle in .375 H&H once refused to open her bolt until I shouted “Fungova, ty stara kurva!” Sometimes you just have to know what language to swear in.
I shall try that the next time one of my CZ527 bolts bind…
It works with electronics, too…
Back in ye olde dayes, when computers were young and you still had dinosaurs roaming the earth, I got stuck with being the “IT dude” for our staff section. The Corps Headquarters got itself screwed hard by Sears Business Systems, and equipped itself with Dauphin laptops, Windows 3.1, and all the rest of the then-current tech. We’d been demonstrated one thing, and got another entirely. The actual delivered laptops were crap, notorious for delivering the Blue Screen of Death out of nowhere. It took months to fix all that, and by the time Sears Business Systems went tits-up, we had computer-like things that sort of worked. Mostly.
One didn’t. I got saddled with that POS on an exercise, or, rather, the LTC in the jump TOC did. Couldn’t keep it running, and it was notorious for freezing or just spontaneously rebooting whenever you were doing critical work. One night, jokingly, I made a show of dragging out the five-pound mallet we drove the camouflage stakes with, and sat it next to the cursed thing after threatening it in front of a small audience with a little percussive maintenance.
That laptop never again rebooted or froze. So long as you had that mallet on the table with it, just behind the right rear corner, it would work perfectly.
New officer came into the section, he got that laptop. I told him about the trick. He didn’t believe me. I demonstrated it, after he’d watched about six hours of hard work evaporate. The hammer worked. The whole thing became a bit of a joke, and so long as we were saddled with that laptop, a five-pound hammer was kept in the laptop bag.
I still don’t have an explanation for that, unless it was something magnetic and that mass of metal at that position did something to ameliorate the whole thing. It could be, however, that raw fear can encourage the inanimate. Sometimes, all you need to do is threaten percussive maintenance…
This is a common “TV repairman phenomenon”.
When the TV set itself starts to work properly at the moment when the repairman steps over the threshold and stops when he steps back.
The only way out is to chain the repairman next to the TV.
I’m an industrial HVAC mechanic by trade and I’ve experienced almost the mirror image of that phenomenon a number of times; like I would get a recalcitrant burner to finally light and stay lit, test cycle it 3-5 times, go to show the customer, only for it to suddenly decide it’s going back on vacation