Why don't we see magnesium guns?

Have you ever seen it burn????

The main issue, as I understand it, is that magnesium is particularly susceptible to corrosion and stress failure.

.38 Special said:

The main issue, as I understand it, is that magnesium is particularly susceptible to corrosion and stress failure.

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This. Pure magnesium is brittle. There may not be a suitable alloy for firearms at a price worth it for production.
Also, it's strong for its weight, but IIRC it doesn't deal hold up as long against abrasions--sliding wear, like those caused by holsters or a slide cycling over it. And it has a tendency to throw sparks if something hard impacts it or rubs it too hard.
Thus why it occasionally gets used for revolvers, but not so much for autoloaders, with the slide wearing at it. Also the concern for its issues with corrosion; you don't want it where it's going to have its coating worn off and that would affect function.

I have a magnesium alloy ar15 lower reciever.
Built it into a pistol.

Scandium is an alloying element in what is otherwise a primarily aluminum alloy. S&W's scandium framed revolvers are only about .3-.5% scandium. Scandium serves an analogous function in aluminum to the way a very small percentage of carbon turns iron into steel.

The Remington Defense ACR lowers were a magnesium alloy castings that was then machines to final shape. Magnesium has similar strength to some of the better aluminum alloys but roughly 2/3 the weight. They do burn but it takes a fair bit to get it burning. The bigger problem is corrosion especially if salts are involved. The ACR lowers where epoxy coated. As long as that coating was intact they could pass standard salt fog testing, if that coating was compromised they lost to the salt fog in very short order.

Metallurgy on THR ......a wealth of info here.

Magnesium
A surge in interest over the past decade has revealed how magnesium alloys and coating techniques can make the most of its attractive properties:

• Magnesium is extremely light: it is 75% lighter than steel, 50% lighter than titanium, and 33% lighter than aluminium.
• It has the highest known damping capacity of any structural metal, capable of withstanding 10x more than aluminium, titanium, or steel.

Aluminium
Aluminium has long been used as an alternative to stainless steel:

• It is cheaper than steel to cast and fabricate, and the cheapest of the metals we’re looking at pound for pound…

From aircraft fuselage to coke cans, aluminium, with its light weight, low cost, and ease of fabrication lends itself to a myriad of engineering applications:

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https://blog.keronite.com/selecting-the-right-lightweight-metal

I vote cost, I have welded enough magnesium to not worry about it burning uncontrollably. It’s not a new thing, Ferrari has used it quite a bit over the years, the VW bug engine cases were cast from it, Homelite even used it for chain saws. However, everyone has drank from an aluminum can…

My dad had a magnesium deck lawn mower.

I can't get a steel deck to last more than about 5-10 years here with the sand and humidity.

The magnesium was brittle- it had some chips from rocks in Indiana where we lived in the 70s. But that deck lasted at least 20 years without abrasion or corrosion- he bought a new mower in the 90s after the second engine wore out, and the deck still looked the same as it did when I was 11.

And it never caught fire.

I heard all that about mag wheels, and I know that they have burned, but I don't think it's as common as it's made out to be.

Not to say it's a great replacement for aluminum in guns. But if there were some part that was suitable for magnesium, I'd buy it. Maybe AR stock or handguard.

Englishmn said:

I have a magnesium alloy ar15 lower reciever.
Built it into a pistol.

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Mag Tactical lowers are prone to to breaking due to the magnesium alloy and aren't very popular for that simple reason. They are prone to breaking at the buffer tube just like polymer lowers. Mag Tac.had to to also add material around the pin holes to keep the lowers from breaking.

Yes I do have one Mag Tactical lower but I would never ever buy another one. I also have one New Frontier Armory polymer lower, again I will never buy another.

Yes magnesium and polymer lowers are definitely lighter than aluminum. But being lighter definitely comes at a cost to durability and strength.

wayneinFL said:

My dad had a magnesium deck lawn mower.

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I still have an old Jacobson deck at the farm, because they too were magnesium.

A company called Mag Tactical made a light weight magnesium lower for a few years but stopped production.
I see Fostech is making a lower called the Flite Elite Series that is a Magnesium / Aluminum Tactical Alloy Construction whatever that is.
From my experience of working at a casting plant for over 30 yr magnesium takes a lot more machinery to work it. To melt magnesium it has to be inside a sealed container covered with a nonflammable gas & after casting it can't be exposed to the air until it cools, so it can't be run too fast that cost's money. The company I worked with finally gave up on working with magnesium because no one wanted to pay the price to have parts made of it.
The plastic industry picked up the slack & started producing almost as strong of parts at a much lower cost.

Dad had a magnesium deck self-propelled Craftsman push mower in the late 60’s/early 70’s. It lasted a very long time before the deck cracked around the engine.

I don't think they use magnesium because of corrosion. If ammonia bore clear gets on your magnesium frame it's going to react before it can be wiped off.
With aluminum you get a very hard aluminum oxide coating a few atoms thick, assuming it's not anodized. It will withstand acid and caustic chemicals at least briefly.
Most Magnesium oxides wash away easily leaving the surface ripe for attack by chemicals.

12Bravo20 said:

Mag Tactical lowers are prone to to breaking due to the magnesium alloy and aren't very popular for that simple reason. They are prone to breaking at the buffer tube just like polymer lowers. Mag Tac.had to to also add material around the pin holes to keep the lowers from breaking.

Yes I do have one Mag Tactical lower but I would never ever buy another one. I also have one New Frontier Armory polymer lower, again I will never buy another.

Yes magnesium and polymer lowers are definitely lighter than aluminum. But being lighter definitely comes at a cost to durability and strength.

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As I recall, these were cast magnesium, they would have been better if forged . . .


Mechanical properties of cast and forged magnesium alloys

You need to toss a vw block or a magnesium rim into a campfire with a good bed of coals, then stand back and put on welding goggles for the next hour or more. It will illuminate a whole desert valley with white light… allegedly.

Stay safe.

Riomouse911 said:

You need to toss a vw block or a magnesium rim into a campfire with a good bed of coals, then stand back and put on welding goggles for the next hour or more. It will illuminate a whole desert valley with white light… allegedly.

Stay safe.

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Most of your camping fire starters are magnesium. Magnesium is also used in flash bang grenades. So yes it is very bright when burned.

For those concerned about a magnesium-framed firearm's propensity to burn, I'd imagine the same event that ignited it in the first place would probably also be bad for an aluminum or polymer framed gun...and for the shooter themselves.

kwb377 said:

For those concerned about a magnesium-framed firearm's propensity to burn, I'd imagine the same event that ignited it in the first place would probably also be bad for an aluminum or polymer framed gun...and for the shooter themselves.

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This is absolutely true.

The main concern with magnesium and magnesium alloys is the overall strength when used in firearms.

Only application of magnesium I'm familiar with in my life is a pair of snowshoes my dad had and a fire starter block I use.

Taurus 856UL Magnesium frame 6 shot snub nosed revolver here. Has yet to spontaneously combust. Not +P rated accordingly.

In my early years as a Tool and Die maker I worked at a shop that made spot welding fixtures for the Donaldson air filter company. (most were for truck tractors but some were industrial applications) We used a lot of magnesium due to the light weight and strength. We took precautions while either turning, drilling or milling it and we always saved the shavings and never allowed them to accumulate. During breaks or at lunch we would pour the shavings in a line with a pile at the end and then light the end. The shavings would burn like gunpowder and give a big poof when the flames hit the pile, it was made more spectacular by pouring some water the end pile as water acts as an accelerant for burning magnesium similar to pouring gasoline on a fire. The fire hazard of solid magnesium is pretty low.