Gun Sabotage

[Larry Lewyn]

I'm writing a movie, based on a true story. One scene concerns slave laborers working in Nazi weapons factories. They want to sabotage rifle and machine gun barrels which they are manufacturing. The Nazi supervisors check every 10th barrel. There is one setup man who handles the initial setup and then an unskilled laborer operates the machine to complete the piece. The supervisor checks the barrel with gauges, micrometers and so forth.
Any help? I'm thinking the rifling would be the best way to mess up the accuracy. Another possibility might be the sights, although it would have to be very subtle.

Any help?
Thanks!

 

[Derek Zeanah]

Would it make more sense to sabotage ammunition instead? Does it have to be the firearms themselves?

 

[JohnBiltz]

No expert, but the easiest and best way to me would be to damage the crown just before installing the flash suppressor. Its going to get noticed though. Eventually It will get backtracked from the field back to the factory and eventually the line most likely.

 

[mjsdwash]

i think i heard about improper heat tempering by FN slaves in this situation, but superior design resulting in no serious failures. If I had to sabotage a firearm in these circumstances, sloppy fire control group machining, and poor hardening would be the best way to make a rifle pass inspection, but fail after relatively little use.

 

[JohnKSa]

If there were an easy way to reduce the rifling twist rate significantly that would probably do the trick. The rifle would be very inaccurate at distance and it probably wouldn't be easy to spot. Rifling twist is not especially hard to measure, but I don't know of a gauge that one could apply that would immediately give a go/no go result for the proper rifling twist.

If part of the acceptance testing is to test fire at distance for accuracy, the problem would be detected. If they just test fire for function it wouldn't.

Of course, at close range--once you get well inside 100 yards--the accuracy issue probably wouldn't make a practical difference since a gun doesn't have to be very accurate to hit a soldier at 50 yards.

I would try to anneal the bolts if I had a chance to sabotage bolt rifles.

 

[jrmiddleton425]

Install the front sight slightly bent to one side. The Israelis had problems as you describe, with Mauser 98K rifles they received via Poland; they found that the front sights were intentionally bent.

 

[sbwaters]

Working in the Netherlands in the early 1970s, my boss described as a teenager having been pressed into service during WWII and transported to Germany to work in armament factories. He said they would do any number of things to slow production -- not just sabotaging the guns, but also the tools. In one instance, he described rewiring drills so they ran backwards.

 

[Larry Lewyn]

Unfortunately, the men don't have access to the ammunition, so that won't work. I like bending the sights. Does anybody have any figures on amount of sight deflection vs.accuracy of fire? Let's say you deflected the sight by 1mm to the left. Would that be enough to throw off the accuracy at 50 yards?

 

[Larry Lewyn]

i think i heard about improper heat tempering by FN slaves in this situation, but superior design resulting in no serious failures. If I had to sabotage a firearm in these circumstances, sloppy fire control group machining, and poor hardening would be the best way to make a rifle pass inspection, but fail after relatively little use.

Can you tell me a little more about the fire control group machining? Is this like the barrels being drilled out on a lathe? Also regarding the hardening process, are gun barrels ground after being hardened? Is hardening something you could tell by eye? Thanks!

 

[Larry Lewyn]

Would it make more sense to sabotage ammunition instead? Does it have to be the firearms themselves?

Unfortunately they only had access to the actual weapons. I guess the ammunition was made somewhere else, athough it would have probably been the best solution.

 

[Wisco]

Does anybody have any figures on amount of sight deflection vs.accuracy of fire? Let's say you deflected the sight by 1mm to the left. Would that be enough to throw off the accuracy at 50 yards?

http://www.brownells.com/GunTech/Sight_Correction_Calculator/detail.htm?lid=13093

So, to throw a shot off by 12 inches at 50 yards with a sight radius of 20 inches, you would need .133 inches of deflection.

 

[Larry Lewyn]

That might work, at least for a movie. Thanks!

 

[FROGO207]

A slightly bent barrel would be hard to detect and might even be blamed on use in the field. Ruger is famous for tightening the barrels too tight and creating a bulge that will degrade accuracy in their handguns---might also do it in a rifle by clamping a gas block on or something similar and be hard to detect with a screwed in barrel. But whatever you do, do not do it in the same place (bent barrel) on every one or skip some in between. Case hardening can not be detected by an inspection by eye. It is a time and temperature thing. Stacking the parts to be hardened haphazardly in the kiln would create hot and cold spots on hammer, trigger, and associated pieces that are hardened and become defective but would only be a problem to the employee if the individual part was tested for hardness. They usually only do a sample here and there when things are working well already. Sometimes even less finishing (polishing the rough areas inside the receiver) can cause things to go wonky as well. There are probably other things but you get an idea.

 

[Larry Lewyn]

Thanks! Case hardening sounds like the way to go! The laborers are familiar enough with the inspection routines to be able to get around them. And the factories did not have first class guys working in the factories as a general rule. Those guys were all in the army. So that could work!

 

[hdwhit]

The workers at the Radom factory in Poland sabotaged many pistols by intentionally improperly heat treating the receivers and/or slides. This is something I was cautioned about when I went looking to buy one.

 

[MistWolf]

What the workers can get away with will depend on quality assurance. No matter how they jack up their work, if the factory inspectors test the firearm and it doesn't work to spec, they'll scrap the bad parts and have them replaced. Sabotage prior to final inspection will only slow production. For the sabotage to have an affect out in the field, the sabotage has to be something subtle that doesn't show up with just a few test shots, something like poorly tempered springs.

First, let's look at this from the story telling angle. Why is the sabotage important to the story? What impact will it have? Is it necessary? Will the protagonist be saved because a minion has a sabotaged weapon? Will the sabotage be foreshadowed will complaints by soldiers, NCOs or officers? Or by showing workers sabotaging weapons at the factory? When the foreshadowing takes place determines how much time and detail is needed to make it work and believe me, you have to have foreshadowing. You can't have a soldier fire his weapon, miss and curse because the front sight was bent at the factory. You'll have your audience going "Where did THAT come from?"

If the front sight is bent, why wasn't it caught by the soldier it was issued to? Lack of training? Poor morale? Didn't the soldier shoot the weapon before this? If not, why not?

Unless you have a very specific scenario in mind, sabotaging the springs so they have a shortened life would work best. It's hard to detect during function testing, but chances the spring will fail increase with every shot and it can be frustrating to troubleshoot. For example, when an AR starts malfunctioning due to a failing extractor spring, the most common thought is that the AR is overgassed, or "Did you try a different magazine?"

I've always heard the stories about Nazi slave labor working to sabotage projects, but I've never seen anything that examined the impact it had on the Nazi war machine beyond slowing development of atomic weapons to a crawl. It would be a good idea to research what the actual affect was

 

[Big7]

In WWII Russia, the ROUNDS were loaded with high explosives every so
often as to blend in with the others.

As we all know an HE detonation is not the same as even an extremely over-loaded
smokeless powder load.

When said detonation occurred, not only was the weapon destroyed (usually a machine gun)
but the crew as well.

 

[Big7]

^^^^^^^^^^^

Maybe WWI as well. Been a while since I read about it.

 

[Pat Riot]

Realize that the Germans serialized most major components in their guns and they kept meticulous records. Should your heroes do anything to serialized components they could get discovered eventually, like JohnBiltz said.

 

[ironworkerwill]

The workers at the Radom factory in Poland sabotaged many pistols by intentionally improperly heat treating the receivers and/or slides. This is something I was cautioned about when I went looking to buy one.

This^ it's what I'd do. Everything will pass unless a scratch test is done on hardened parts.
Adding corrosives to springs before oiling , annealing firing pins, and possibly over hardening other key parts like lugs or even the stock tang.

 

[Larry Lewyn]

What the workers can get away with will depend on quality assurance. No matter how they jack up their work, if the factory inspectors test the firearm and it doesn't work to spec, they'll scrap the bad parts and have them replaced. Sabotage prior to final inspection will only slow production. For the sabotage to have an affect out in the field, the sabotage has to be something subtle that doesn't show up with just a few test shots, something like poorly tempered springs.

First, let's look at this from the story telling angle. Why is the sabotage important to the story? What impact will it have? Is it necessary? Will the protagonist be saved because a minion has a sabotaged weapon? Will the sabotage be foreshadowed will complaints by soldiers, NCOs or officers? Or by showing workers sabotaging weapons at the factory? When the foreshadowing takes place determines how much time and detail is needed to make it work and believe me, you have to have foreshadowing. You can't have a soldier fire his weapon, miss and curse because the front sight was bent at the factory. You'll have your audience going "Where did THAT come from?"

If the front sight is bent, why wasn't it caught by the soldier it was issued to? Lack of training? Poor morale? Didn't the soldier shoot the weapon before this? If not, why not?

Unless you have a very specific scenario in mind, sabotaging the springs so they have a shortened life would work best. It's hard to detect during function testing, but chances the spring will fail increase with every shot and it can be frustrating to troubleshoot. For example, when an AR starts malfunctioning due to a failing extractor spring, the most common thought is that the AR is overgassed, or "Did you try a different magazine?"

I've always heard the stories about Nazi slave labor working to sabotage projects, but I've never seen anything that examined the impact it had on the Nazi war machine beyond slowing development of atomic weapons to a crawl. It would be a good idea to research what the actual affect was

Thank you for the detailed information. I am somewhat handicapped because, although I am familiar with metal working, I know nothing about guns. I like the idea of incorrectly hardening or tempering the springs, because it seems like this might be easier to conceal than bigger parts. And I presume they would not fail until they were actually in the field. I think you already mentioned that.

I am somewhat constrained by the fact that this is a true story. The actual sabotage that occurred, as far as my source could remember (he passed last year), was limited to removing parts from or damaging the machine tools. It pissed the Nazis off, but they had no good way of narrowing down the suspects and they need the workers badly, because they had huge armies to supply. Things changed later in the war. But in late 1942 the Nazis were still preserving the lives of their slave laborers, at least in Berlin.
The motivation was simple - they wanted to injure the Nazis and help the Allies, as long as they could do so without getting killed. I wanted to add a little more sabotage for dramatic effect. I'm comfortable with stretching it that far. Thanks to you and everyone who has replied.

 

[JeffG]

Annealing the chamber portion of the barrel would seem the simplest.

 

[mjsdwash]

Can you tell me a little more about the fire control group machining? Is this like the barrels being drilled out on a lathe? Also regarding the hardening process, are gun barrels ground after being hardened? Is hardening something you could tell by eye? Thanks!

not so much the barrels, but the bolt lugs being heated to the point of glowing red, without controlled temperature, quenching or oven time can result in some very brittle steel (look into the 1903 springfields if you want to read more, not sabotage, but simple bad manufacturing practice). Machining the trigger/sear/hammer/striker or whatever to only have a slight amount of metal interaction, but keeping it untempered, and soft will result in a working mechanism that fails after a few tens to hundreds of uses. The soft bolt lugs or over hard receivers can be extremely dangerous, whereas the trigger work would result in a non functioning rifle, that may be dangerous if you want it to be

 

[CapnMac]

.accuracy of fire?

The acceptance measure for Kar98K, IIRC, was 5 or 10 shots into 800mm x 800mm square at 200m. So, bent sight blade would not be noticed until much later.

Cross-threading or stripping the threads on simple things--like barrel bands, sling swivels and the like. Things which would not deadline the rifle but would lower soldier morale.

Ah, here's an idea. The sight base on the Kar98K is soldered to the receiver. Skewing the jig used to solder the sight base would mean that all the sight bases would match "spec," but would be wrong. Mismatching the shight graduations and the notches the sight base indexes to would be hugely subtle. It would also be very hard to detect. Mis-grinding the sight base ramp would also be effective--and extremely hard to detect.

The best thing, though, would likely be a mis-cut of the chamber, which could be out of spec for length, or off center or the like. The boring jigs could be blamed for that, as well. ["Ich bestellte nur folgendes."]

 

[hso]

Over hardening and under hardening would lead to field failures and can't be detected with the eye in production. The challenge would be to do it close enough to spec that the weapon would function properly for the first several uses and then fail in the field. Broken firing pins or bolt lugs due to over hardening and deformed lugs due to under hardening would take time, but disable the weapon. Doing the same to sling mounts would be more subtle, but a rifle that can't be slung because the mounts break or deform and pull out make it difficult to march with the rifle or use a sling for accurate fire.