This is a very long post, but hopefully some of you might find informative! If you don't want to read all of it, skip to the very last part about preventive and remedial action.

Let’s start with how this AK survived three mud immersions.

Most probably because of differences in AKM specs and even a bit of fitment as well, but the spec is what's very important, that differs in as crucial components as bolts and gas port sizes in different civilian AKMs and even military AKMs as well. There’s nothing magical or unexplainable about it, some AKMs will "power through" more debris and for longer than others because of that. How overgassed is the question and then comes quality, and how correctly the parts are fitted. This specimen here managed to survive for that long because it had better fitment where it needed to be and had a larger gas port and indicates that this topic of mud is not a simple one beyond the point of AK specific factors, as other factors are always at play that make mud tests a very complex topic..

Full video: https://youtu.be/O0-Im1pjfIU 

Some observations about this test:

What I found very strange is the struggle with the magazine release lever and the safety selector, it might indicate too tight fitment of these parts on this Turkish AK as this was not a struggle with any AK mud tests I’ve seen on InRange or other channels where those elements were exposed to mud. Or it could also be because of the stickiness or the debris inside of the mud, but I’m leaning towards a combination of the two.

Also, it did not fully go into battery at least one time due to the debris yet it kept firing, it happaned a lot in Garand Thumb’s tests on the Galil ACE. https://youtu.be/e-kE_wbGLhE?t=1638  More on that topic later.

But still after the third immersion this Turkish AKM failed in a similar way the Romanian WASR on the InRange test. Again: it just managed to power through much worse than the InRange tests and for longer. At the end, it also turned into a manually operated gun because there was too much debris for the spring to handle, and then the debris slowed the bolt down for a failure to eject and then it wouldn’t close with a round because of the debris in the chamber, then a double feed concluded the test.

Did mud kept getting into the gun? Yes, just slower. Is this performance great? Absolutely, especially for such open design. But is it fully optimal? 

Some of you already know, powering through is not enough for staying reliable in the long run. You also need a sealed action.

However this can be enhanced. Some designs are easier than others to enhance. But more on that towards the end of the post. 

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Let’s get back to the other factors at play that apply to everything.

How much of the mud stuck onto the vulnerable areas, fell off or seeped into the gun?

Obviously the state of internal components is also important and I would also add the power of ammunition used that will affect your bolt velocity on guns and can help them power through a certain amount of debris, giving you just a small edge. Adverse settings on gas keys can potentially do more on gas-operated firearms.

And the big one:

Mud variables!

There are several different types of soil just as there are different types of mud that occur in nature. 

Made of sand, dirt or clay (or a mix)

It can be runny watery mud that likes to seep into the action. It can be somewhat solid that impedes on the bolt carrier and falls into it. And so on and so on until you reach clay-like mud and actual clay. 

And then comes other variables, like what does the mud also contain? Does it contain small rocks? Does it have congealed chunks? 

Having presented all that, some guns might do better in the given type of mud but do worse in others. That depends on their external receiver tolerances and internal tolerances and design, fitment of parts, gassing,operating system, cyclic rate, bolt throw etc 

Ideally when it comes to reliable function in a great many conditions you'd want tight tolerances externally around the bolt carrier and receiver, yes you can make strategic cuts on the bolt carrier if you want to, and they do not necessarily have to extend into the receiver for example on the top or bottom of the bolt carrier, just a small horizontal cuts that give a bit of a separation of the bolt carrier and the receiver.

On the flipside, you’d want larger tolerances between internal components and enough space inside the receiver with areas of soot and carbon can accumulate apart from the debris that can get into the gun. For example very watery mud containing very fine particles. Or very fine sand also.

And yes you can “cheat” with dust covers and indeed with modification but more on that after this section. 

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Mud examples:

Example of “sus mud”: https://youtu.be/juIjXQG1WMc?t=38 (The "SIG flavored" NATO mud from the MCX promotional video)
https://imgur.com/a/E5Bfofp
Whatever this thing is, it is probably more of a lubricant but hey, they have other tests featuring this exact type of mud so they are at least consistent…

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Examples of many types of mud, but clay-like: 

(InRangeTv’s mud test playlist:.
https://www.youtube.com/watch?v=LyXndCxn9K4&list=PLj9u4Ts2NpEv4Fnwx2_ig4wVqiONfH1me)

You get all kinds of mud of differing consistency, because they tested a lot of guns at different times and made different mud. Although there were tests where the testing was done on the same day right after each other so the mud wouldn’t have dried up. Like the first AK and AR tests.

https://youtu.be/YAneTFiz5WUhttps://youtu.be/DX73uXs3xGU

There are rocks and debris in the mud sometimes. Sometimes the mud sticks, sometimes it falls off, but that also depends on the rifle's finish or receiver design. And that can absolutely play a part in how much mud sticks onto it and for how long after firing or shaking it off.

What the InRange tests do well is they eliminate the chunks through mixing. So whatever mud they got on that day seems consistent. So tests like the InRange and this Turkish test, where even if it’s one gun in one type of mud: Can potentially be more consistent than for example the many videos that involve mud puddles like the next video coming up or just wet earth like that Garand Thumb mud test video.

But ALL of these informal and largely inconsistent tests are STILL worth looking at in my opinion, because they might better reflect the proverbial “field” conditions and expose areas on designs that are vulnerable.

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Example of clay-like mud: (This 1ShotTV video. https://youtu.be/xFldS6aLPTE)

In this video both a WASR AKM failed and a BCM AR-15 turned into a one shot gun (dust cover open on the AR, AK selector down but we know having it up wouldn't have made a difference.)

Clay likes to stick BAD and it was also full of all kinds of debris, this is a very hard test to pass.

The interesting bit here is the remediation part.
Where dunking the AKM in water and cycling twice after got it back to running . While doing the same to the AR ended with making the stoppage worse and a struggle with getting it fixed. The water probably made the problem worse and made the debris travel more inside the upper and work its way more to the chamber area.

As you can see, it is very hard not to have inconsistencies without having a controlled environment and the right equipment. Maybe a possible solution is digging a big mud pit or have one big mud pool filled with one type of mud. And throw every gun you want to test right at the same type(MUZZLE CAPPED!) or right after each other at a time when the mud doesn’t really dry up fast. But then the debris would still be there. It is hard to do this pebble to pebble without having rocks and other debris in the mud also, and you need filtration to do that or just buy a lot of off the shelf earth or sand that is more “standardized”.

So yes, a lot of variables are at play in mud tests. Yes, standardized mud tests exist and that dictates batch testing in precisely consistent types of muds, or just one type of mud in a controlled environment. 

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Addressing issues, modifying guns to perform better in mud. (I will focus on the AR  and AK but some of the modifications can apply to other guns as well.)

The AR.

(A good example of a gun that doesn’t need much modification.)

https://youtu.be/YP6rwfSj9iA?t=8 The InRange video in a mud where Ian McCollum crawls in mud.

The video on Full30 is unavailable but if you are a long-time viewer of InRange, you might remember the AR-15 malfunctioned here and the issue as Ian and Karl found found was mud seeping in from the trigger, and switching it to HK 416-style trigger will help seal the trigger and the wheelbarrow tests were conducted with KE arms SLT triggers of similar semi-sealed design. (If you have the video, please do share it in the comments.)

I’d also mention that  the receiver gap could’ve been an issue with this type of runny mud, of, where very small sand particles and exactly that type of runny mud can seep through as well as the tiny openings around the BCG. 

The issue of the lower was addressed in the HK 433 actually by adding internal shelves.

https://imgur.com/a/tz5etJ3

But other than that the AR-15 is of all popular designs, the perhaps most ready for muddy environments. It has a smaller ejection port AND ejection port area where mud can accumulate or stick onto. Plus the Stoner gas system actually aids the reliability. It blows out the excess gas from the port holes. Similarly to gas piston ports on conventional external piston designs. Obviously in this case, the gassing is important as well, and how gas efficient the BCG is. And for that build quality also plays a factor in the AR as well, if you’re aiming for that extra bit of reliability that is. Why an extra bit? Because the AR is again, better sealed, even within a wide range of guns that spending the extra money might not give you so much better performance for this case. 

(LMT MARS-L)
https://imgur.com/a/SjRfyye

Yes, you can “cheat” with port covers. They work. And that BCM AR-15 would’ve survived the clay test if the port cover was closed.

https://imgur.com/a/NJdcI6W

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The AK. (and potentially others) 

AKs as you’ve seen have much bigger issues, due to the open design. The most vulnerable spot is the unprotected frontal area of the ejection port where there's a clear path to the locking lugs, and the chamber.

Mud can seep and fall into the locking lug area, which is not even the main problem due to the Garand locking lug design being more tolerant to debris, unless it's a large chunk of mud that prevents the bolt from closing. The bigger issue is when it gets fed into the chamber and accumulates inside of it. 

You can both happen on the slow motion shots on InRange test and this Turkish test also. And I’d also like to mention the stepped top-cover and bolt carrier design where mud stubbornly hangs on and falls into the large ejection port. While other designs it falls off easier. The only worse gun that has this problems I can think or is the AUG. It has an up-turned ejection port. Maybe firing canted might help?

You can use boosters, suppressors that introduce more back pressure and make other gas operated rifles cycle faster. (To delay the inevitable even further yet again.)

Better solutions? 

Karl from InRange shows what exactly the problem is on the AK and thinks of possible solutions. https://youtu.be/3gKc7VF0MZQ?t=235

The AK-107 top cover and bolt carrier design addresses a large part of this issue. I can see a bit of Dragunov influence there…

https://imgur.com/a/ml0KcFx

(The AK and Dragunov don’t have anything in common, only the Garand-type locking lug trunnion)

Dragunovs save the Garand-type locking system?

Interestingly enough, when the Russians modernized the Dragunov MA in the mid 2010s they abandoned this exposed design. They sealed that frontal exposed area, on both the SVCh DMR and the AM-17 PDW. Also, they don't have the quarter-exposed stepped carrier and stepped receiver design.

https://imgur.com/a/OwilxkZ

It is worth mentioning the Dragunov bolt is in-line with the carrier and it is shrouded. While the AK has a bolt hanging off from the carrier inside the receiver. I don’t think one is more sealed than the other but they are more sealed than for example the exposed designs like the AR-15 and 18.

(AKM BCG and a front trunnion)

(Dragunov BCG)

(AM-17 BCG)

(AR-15 BCG)

https://imgur.com/a/IdpxqMl

That can actually be an advantage, especially if you have longer bolt throws.

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Modifying charging handles.

The L85A2 charging handle is designed to clear mud off the ejection port, such was it’s trigger also. Having the ability to attach such a solution can absolutely make a difference in mud. In the case of a normal AK this has to be shaped differently.
https://imgur.com/a/QxSIAq5

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Moving dust covers.

One could design dust covers for the charging handle slot. They do not have to be permament and they can be attached via pinned slots. I'd go with the one the FNC has. This thing works and is better than the SIG 550s rubber gasket in my opinion and FN also tried to do that way with the CAL. Plus the FNC style of dust-cover tends to function in extreme cold weather despite it being a larger part of metal, impacted by the bolt. That is important for it not to impede the travel of the bolt carrier.

And here is an example that it really doesn't impede it. (AKV-521 freezing test: https://youtu.be/pbQp6ZRjnUQ?t=51)

(AK5)
https://imgur.com/a/mqrjoUk

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Using plastic mags instead of stamped steel. 

This may sound funny but it can help. Plastics offer much less friction than metals do, especially if the treatment is worn, very important when things get sticky or gritty.

With AKs and most guns mud ingestion from the magwell area is not an issue. As you can see on the post video(at 5:20) but this InRange video shows it better,  https://youtu.be/NgP6Fea8zM8?t=400 

You can see the sides of the magazines are clear at the top where it seats into the magazine well, the issue is mud falling onto the feed lips and rounds from the ejection port.
https://imgur.com/a/QbPUY1X (ran out of postable images)

And at last I'd go back for AK specific stuff, moreover back to the spec!

Using a good AKs with good fit and finish on at least the external components and correct gassing. 

So it doesn’t have a million holes in the top cover like many AKS do, that will allow more mud to seep into in exactly the spot that was discussed earlier. But in other areas as well.

So I’d say using AK-100 derived guns instead of AKMs or even AK-74s of a billion different specs. is beneficial for that reason.
Also, 100 series guns may also help in reliability overall, as they feature numerous little enhancements to the system and they feature better finishes and overall the 100 series are just better AKs than the classic AKMs in my opinion but are a bit heavier.

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Preventive and Remedial action.

Yes, swiping not just shaking as much mud from at least that critical part of the AK, or ANY gun before shooting for that matter will increase the chances of reliable function. Especially if it’s a sealed enough design.

This person is a bit too enthusiastic for some reason but demonstrates how that remedial action works on an AK covered in mud: https://www.youtube.com/shorts/jNsrgx8len4  

The AR is a good example for water. If the AR user’s gun ends up in water then they have to drain the barrel, upen the action and drain the receiver bolt and receiver, and give it a shake and get back to work..

Example: https://www.youtube.com/watch?v=V05SjVMtARA (here there was no round chambered in the gun)

Example: https://youtu.be/2a9lZO74YCE?t=324 (Doing partial remediation :NOT opening the action and ONLY letting the barrel drain can result in malfunctions in the AR as Regular Guy LLC demonstrates)

The only question for remedial and preventive action, does the situation permit the user in doing so? 

Are mud tests irrelevant?

Mud tests are NOT unimportant or unrealistic (when done right and not pouring stuff into the gun) OR irrelevant.

Infantrymen won’t use special techniques under extreme stress and exhaustion in order not to get their guns dirty. They will absolutely fall on their guns in mud or anything really when they have to get down. Their guns will get muddy when travelling in muddy environments and so on.

At the end of the day, knowing your gun and its intricacies, training with your gun in different environments, knowing how to work with its limits is what's MOST important!

Media content sources: Forgotten Weapons, InrangeTV, Modernfirearms. net, Sig Sauer USA, Reddit, Kalashnikov Concern, milmag. pl, Sarsilmaz, Lewis Machine and Tool, Recoilweb)

(I have no control over the links from imgur. com, if any entity buys imgur and decides to reassign links in the future, they might get replaced with something irrelevant to the subject.)