Pretty nifty way to get a deep clean

Cleaning a gun with mostly water is just strange to me.

That is what dentists do.
Heck, that is how autoclaves work too.

Ultrasonic Gun Cleaners | Brownells

Would this offer any advantage over a proper conventional cleaning?

Avoids the detail strip that very occasionally should be done. How often depends upon operating environment.

Also gets nooks & crannies that many/most folks aren't going to bother with or really can't reach.

did this to an LCP that rides in an Alabama pocket holster pretty much full time. Maybe a couple of hundred rounds through it, cleaned after sessions. Turned the solution black. Blew it dry, bit of Barristol with a thin application of red rail grease, good to go. Do believe this is going to become my go to for semi's.

Ultrasonics can offer a lot in getting assembled parts clean.
You can put a dirty part in and watch as the dirt boils off in a cloud.
We watchmakers have used them for many years to allow cleaning watch components without having to totally disassemble them.
Same thing works very well with guns for deep maintenance.

For normal maintenance US cleaners are often slower then normal cleaning, but for the occasional deep clean they're excellent because they don't require actual disassembly.

US will NOT remove copper fouling, and usually won't do a lot for leading, so you still need to clean the bore and chamber.

One thing not mentioned in the video is that ALL lubricant will be removed even from tiny crevices or holes normal cleaning can't get to.
After cleaning and drying you have to get a lubricant inside everywhere both to lubricate and to prevent rust.
One that works well for this is CLP Breakfree because it spreads and creeps into all areas.

The best way to do this is to spray a fine mist of lube, but CLP doesn't come in a fine mist spray, so I have used an airbrush to spray it....(DO NOT breath the fumes, you won't like it).

Also be very careful what cleaner solvent you use, some harsh soaps like Simply Green and Greased Lightning WILL EAT ALUMINUM, and will do it faster in a cleaner.
If in any doubt, test by running a piece of scrap to see if it gets attacked.

For solvents you can buy products made for guns, use hot water and Dawn, or cheap paint thinner.
If you use a flammable solvent NEVER walk away even for a minute due to the fire risk.
In addition to the plastic bag trick, you can use flammable solvents like lacquer thinner in a small glass, plastic, or metal container with an inch or so of tap water in the tank.
The US waves pass through the container.
This allows cleaning and brightening small parts like trigger assemblies.

All solvents work better when hot so either run the tank for a while to heat it up or warm the solvent.

US works better if parts are not laying on the bottom of the tank, use a basket or hang parts with wires.

One caution: KEEP YOUR FINGERS OUT OF THE TANK. US waves and bone marrow don't play well together. This isn't instant, it's cumulative, so just don't start.

I’ve done parts in a sonic cleaner and they work well. The M&P series of pistols has a cloth covered pledget within the trigger spring somewhere that supposedly gets soaked and can affect its function. Check out this YouTube video on sonic cleaning a S&W M&P Sonic Clean. Guy does his whole M&P. There is something very therapeutic about watching him sonic clean and rinse with a hose. Gun is totally clean. He follows up with an ultrasonic lube bath.

GUN CLEANING (ultrasonic) - YouTube

I've got a small cleaner that works good for small parts. I put a couple inches of water in the tank and put the parts in a plastic food tray filled with WD-40. The tray keeps the water and tank clean. The WD-40 and ultra-sonic does a great job of melting the gook off.

Stripped components could be thoroughly dried and lubed as needed. Am skeptical of doing it with assembled parts though.

Field stripped parts are the attraction to the Sonic cleaners. Some guns like Glocks are easy to take down to the bones so no real reason to do so, but I’ve watched a few M&P detail strip videos and I wouldn’t want to do that.

The man in the video is (in my opinion) pretty foolish for carrying a gun for SD without cleaning it for over a year! That is just asking for trouble! I would not even do that with a dedicated Range gun, no less an EDC gun.

Secondly, I'd bet dollars to doughnuts his process, including blowing out the water with an air compressor and drying the gun with a hair dryer would take many times longer than a proper cleaning with the traditional method. Personally I'd not use water to clean the inside of a gun. Too easy to miss moisture left inside, despite his compressed air and hair dryer afterwards.

Thirdly, he stated no one enjoys cleaning their guns - well I must be a "no one" because I sort of enjoy it and enjoy knowing I have a clean carry gun.

My thoughts exactly. Put a small spring with a plunger in a tiny tube and hope that you can dry it out completely? The only time I’ve used ultrasonic cleaning on a pistol, I completely disassembled it. That also ensures you lubricate everything that needs it.

Ballistol comes in an aerosol and is a good all around lubricant IMHO.

Our armorers used the US cleaning during their semi annual inspection of all our weapons including our M&P40 1.0s. BTW, you wouldn't believe the crud that can come out of a "clean" heavily used AR. Besides aiding the detail inspection, it took care of the sidearms of those less dedicated to proper maintenance. SFAIK (The lead armorer was a good friend.), the "tampon" was unaffected and only the usual 5K rounds/5 year parts change outs were done as required.

Yes, during a published years prior torture test of a Sigma that involved dunking in a water filled barrel to cool it, the tampon disappeared and premature spring failure resulted. However, changes were apparently made and I doubt anyone else is going to try to burn through 10K rounds in a day.

So far as lube, I've been a dedicated user of Dri-Slide for over 50 years. Moly disulfide dry film lube in an evaporative carrier. Goes on wet-and creeps into places-then dries.

I inherited an ultrasonic cleaner and a barrel of Carbon-X when I shut down our hangar. It was used for cleaning helicopter/jet parts. My AAC Scarab suppressor loves it. Carbon-X is incredible stuff.

Thank you for your very informative post, I’ve learned a lot. I’ve been thinking of getting an ultrasonic cleaner and basically know nothing about them! The fact the US waves pass through a container just might be the tipping point for me. I can see the benefits of it, cleaning small parts of multiple guns at the same time for instance.

Our issued and authorized weapons were inspected yearly by the armorers, and they used ultrasonic cleaners. There were other reasons to clean that way, mostly to allow inspections. In reality, any firearms that won't work dirty is probably flawed. IIRC, I first heard that from Rob Leatham. Pat Rogers said the same about ARs, and he had a bunch of them that went 20K-40K rounds without cleaning, just lube.

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NHI, 10-8.

65Whelen - Quick, throw the WD-40 in the trash and don't think about
it ever again. Whew.....Saved another one.. your welcome. Mike

as a follow-on to simple green, castrol super clean, and many others, they will really mess up anodizing and polished aluminum or magnesium. You can order an Aviation Simple Green approved by the FAA for use on aircraft as it doesn't affect surface coatings, or conversion coatings, or corrode aluminum, magnesium, etc.
3rd gen alloy frames have a clear anodizing for instance.

That zip lock bag trick is awesome. Uses less cleaner too.

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NRA RSO