Saturday, August 16, 2014

The MIM meme...

So, here's a closeup of my Bodyguard 380, manufactured in August of 2012, all field-stripped. Notice anything (other than that I should have stopped down on the aperture for more DOF)?

Growing mold.
See the mold line atop the chamber? Unlike the multipiece barrel of the Walther PPX and its forged barrel housed in a MIM breechblock, this is a one-piece barrel, machined from a MIM blank. I never thought I'd see the like.

I didn't know such a thing was possible, as the internet has long informed me that powdered metallurgy is responsible for parts breakages, guns malfunctioning, rains of frogs, and the heartbreak of psoriasis. (This is, ironically, the very same internet that is practically wetting itself with excitement over the possibilities of "3D printed guns". Shhh. Don't tell them; it'd break their little hearts.)

.380 ACP maximum operating pressures are, of course, only ⅔ of standard 9x19mm and barely more than half those of 9x19mm +P. But they're about the same as .45 ACP. You'd think if there was a rash of BG380s going high-order in people's hands, we'd have heard about it by now, no? I've got a little over two hundred rounds through mine now without a malfunction, which isn't a lot by any measure, but probably more than most of them will ever shoot. Most will shoot a box of ammo, plus how ever many rounds it takes to pass a particular state's CCW licensing regime, and that's it.

In my book, these little pocket .380s like the BG380, P3AT, and LCP are largely disposable anyway, so complaints about their soulless qualities are pointless. Their primary virtues are light weight, compactness, and a price low enough "that every man (and woman) be armed." This is as volkspistole as it gets right now; in a perfect world, these things are sold in blister packs next to the disposable vacation cameras.


og said...

Cripes, you don't know the meaning of heartbreak buddy!

If you hop on 74 and follow it to the Illinois river, then exit Illinois 6 and take it to it's end, you will practically be in the parking lot of a little company that makes every one of the slides for that cute little pistol. Very, very nice people-I worked on those machines, installing some high order tooling. You would be surprised as to how much of that slide is NOT machined, they come in a state of remarkable completeness right from the foundry. I would already have one, but for the fact that I have a Government 380 already. Though owning two 380 self loaders might become mandatory soon.

Mike_C said...

and the heartbreak of psoriasis
I remember those commercials as a kid and thought psoriasis was some sort of cardiac condition. Then I finally looked up the word, and felt pretty silly for conflating the two. Well, it turns out there are links between autoimmune diseases and cardiac problems. A cursory search on Pubmed turns up 407 hits (lots could be irrelevant though), but Copenhagen researchers (using the Danish national databases which are a goldmine for epidemiologic research found href="">increased risk of heart failure* with psoriasis with greater risk associated with more severe psoriasis.

*"Heart failure" is a term of art. Having anginal chest pains, or even having had a prior heart attack, does not necessarily mean one has heart failure.

Bubblehead Les. said...

I look at those Pocket .380s as a perfect example of Heath's Law: "Never carry a Pistol that you can't afford to have Locked Up in the Police Evidence Room."

Commander_Zero said...

The award for ".380 With An Expiration Date" should go to Smiths old SW380/BabySigma. Utilizing the metallurgy that made RG famous (turns out Rohm WAS built in a day...less than a day, actually) the SW380 was listed as having a usable life of measured in days if you fed it more than a half case of .380. Add a unique cost-saving magazine retention method unique to the SW and you get a gun as popular as a 94 Nambu but without the good humor behind it.

Tom said...

When I saw this my thoughts immediately sprang to my everyday carry gun, a plain Jane black Ruger LCP of the slightly newer vintage. Just stripped and looked at it, and....doesn't look like any MIM work to be found here. Not really surprising, considering Ruger's experience with casting over the last several decades. What really struck me was how THIN the barrel and chamber hood are! While they're apparently cast and machined in the conventional manner, the barrel has an integrally tapered bushing on the muzzle end, presumably to aid in tighter lockup as in goes into battery. More than anything else I'd be this explains why it's a far more accurate mousegun than it could be expected too. The trigger is clean and smooth and probably about 6 or 7 pounds, and it's eaten every single round of ammo I've fed it, JHP or hardball.

The only thing about the MIM setup on the Walther PPX that unsettles me a bit is the shot of the barrel and chamber. Clearly the barrel is machined and nicely at that, but....tell me it's not just pressed into the chamber hood assembly?

Volkspistole indeed, but it appears that Ruger still charts its own path (quite successfully for the most part too).


KevinC said...

1911's are to pistols what katanas are to swords.

Will said...

" disposable vacation cameras"

These things still around? Just threw away a couple I had left over from 10+ years ago. Carried them for my FSP job.

Anonymous said...

That's funny, Honda has been using sintered metal techniques to manufacture hypoid bevel gears (the final drive on a Goldwing) for a couple of decades. Everyone 'knew' that there would be broken down Goldwings on the side of every road, yet it didn't happen. A lot of gears are now made using the sintered powder method due to the cost savings over machining.

Taking a quick tour of the internet, there are MIM alloys that will produce a steel with up to 290,000psi tensile strength and the density of the MIM steels is almost 100%. I was taught 30 years ago that 250,000psi was space shuttle stuff.

I would bet that the MIM barrel in your Bodyguard is made of better steel than in an original 1910 Browning. The techniques have evolved from 'that looks like the right shade of red, quench it now' to where the temperature is controlled to within one degree F and the part is then quenched in the selected special oil for exactly the right time.


billf said...

Tam,I think you have already figured this out by your own experience,but I will add my 2 cents anyway.Years ago,when powder metallurgy was first being played with,we suspected it would only suffice as bushings and spacers,and not take any kind of torsional or leverage stress.But it is still steel,after all,(well not always but in this case),and due to the high pressure under which the parts are formed,actually exhibits denser structure and higher strength than some types of machined parts.
They now make some gears by this process-for cryin out loud-and they used to make firearms out of brass.So,there's all that

Anonymous said...

It could also be a cast steel barrel, using a permanent mold. Investment casting would not leave a parting line like that.

You think S&W would have at least smoothed the breech block where the parting line is visible all the time.

Sport Pilot said...

OK I'm perplexed on this one then. Is the entire barrel MIM and then rifled or MIM with a sleeved rifled insert? As to the durability issue only extended use will tell that story.

BillB said...

"in a perfect world, these things are sold in blister packs next to the disposable vacation cameras."

Dream the dream!

DaveFla said...

Al in Ottawa- not that I really know much about it, but I'd prefer a well-designed MIM gear to one with micro fractures and scratches from machining. 30 years ago everyone wanted forged aluminum pistons, but today's minimum skirt, low friction cast units are just one more thing that makes my '72 Dodge look like the stone axe it was.

Angus McThag said...

I think what we're seeing is the convergence of the tech of MIM improving and parts that were designed to use it.

The bad reputation that MIM earned was using it to make parts that were complicated to machine and made from tool steels.

There's parts I don't think will ever be successfully MIM'd; but there's a whole slew where it doesn't matter. I was going to mention the 1911 but I can't recall which parts are/were bad to us MIM on now.

Anonymous said...

Dave, I'm in aviation maintenance, where light weight, compact size and reliability are paramount over cost. The reduction gears in a turbo prop engine or a helicopter transmission start as drop forged blanks that are machined, polished and heat-treated. They are the best gears that can be made but the cost is astronomical. Sintered and MIM can't compete with forged and machined for performance but forged and machined can't compete on a cost basis.

Regarding pistons, in the past few decades spin casting has become commonplace. In traditional casting molten metal is poured into the molds and gravity does the rest. This can leave bubbles known as voids in the metal so castings had to be thicker and heavier than forgings. With spin casting the molds are spun at very high speed and the metal is poured in. The centrifugal force (many, many Gs) packs the molten metal into the molds, eliminating any voids and producing a dense, strong metal structure.

Two centuries ago every piece of steel in a firearm was shaped by beating on it with a hammer while it was red hot. A century ago everything was machined from solid stock. During WWII sheet metal stampings and electric welding were used to cut costs. Bill Ruger used those techniques to create his Mk II pistol and then industrialized the 'lost' art of investment casting in the '60s. The '70s brought sintered metal technology and the '90s MIM. Now comes 3D printing. Can you imagine what John M Browning could have done with all these techniques at his disposal?


Tam said...


I'm very familiar with the LCP and its antecedent, the P3AT. I have a good closeup of the coned barrel bushing to which you refer here.

Smart people to whom I listen about manufacturing are guessing that the breechblock on the PPX goes into the furnace with the barrel and feed ramp already in situ.

Tam said...


"1911's are to pistols what katanas are to swords."

If by that, you mean "gushed over by mawkish fanbois on the internet who don't really understand them", then sure. ;)

Dave In Indiana said...

I've worked in the machining industry pretty much for ever and have seen similar flash lines on forgings, which due to grain structure are considerably stronger than similar items machined from bar stock. Not saying that is or is not a MIM product, just mentioning another possibility.

Don M said...

"In my book..." I had a moment when my heart got into my throat!

Tam, you really ought to write a book!

Doubtless I have said that before!

Anonymous said...

As Dave said, forging dies often have parting lines too, as can investment molds. -- Lyle

Goober said...

I have psoriasis. At one time it was over 84% of my body. I also have psoriatic arthritis and as I'm writing this I'm sitting in the waiting room of my cardiologist waiting for a pre-surgery test. I'm 34 years old.

Hell yes psoriasis is linked to heart problems. I'm living proof.

Gonna remove a mass on my left atrium and ablate a bad node causing atrial flutter, afib, and av block. Tell me about the goddamned heartbreak of mothereffing psoriasis.

Goober said...

Not that great, but still imbued with mythical powers they don't actually possess?

I agree...

Goober said...

Damnit, I knew I shoulda read the entire comment thread before replying to kevin.

Curse you, tam!