Color Case-Hardened Thompson (Ugh)

[reconbob]

A couple of weeks back a guy sent me a trigger frame which had the T-slot for the magazine damaged because he did know what he was doing and tried to hammer it off the receiver, so the mags would no longer fit in the T-slot.

 

I told him to send the frame figuring I could file out the dents and dings so to mags would fit.

 

I get the trigger frame and the entire frame has been color case hardened and is as hard as glass and cannot be filed or machined. I could not believe anyone would do such a thing and sent the frame back.

 

I just found out that AO/Kahr is to blame for this as they now offer a color case hardened version of the gun they call the Chicago Typewriter. Going by the trigger frame I saw this is one ugly finish.

 

When I think of color case hardening I think of an S&W hammer, or an SAA frame, or some Luger parts which are silver colored with what Ill call the rainbow effect.

 

This Kahr gun - judging by the trigger frame has a flat (probably sandblasted) dark blue-black finish which is mottled with tan/yellow splotches and pink striations. It it one ugly finish and looks like hell.

 

Plus I dont think the gun was designed to have the parts hammering away on a hardened receiver. I would avoid one of case hardened guns.

 

Bob

[Countryboy77]

Very Ugly . I thought West hurley made ugly actuators but Kahr looks something like a little mushroom .Actuator/ bolt handles just get taller and taller. Phallic almost.I do like the wood.

Edited April 18, 2022 by Countryboy77

[BRMCII]

 

"Plus I dont think the gun was designed to have the parts hammering away on a hardened receiver. I would avoid one of case hardened guns."

 

Casehardening is only a surface effect with minor penetration, 1 mm or thereabouts, so the inner surfaces of the receiver are not affected and not "hardened". FWIW

[Countryboy77]

Semi auto is also a different animal.Receiver is thicker because no oiler cutout ect. So theres more steel and double springs to slow the bolt recoil spring and striker spring. Not to mention semi only so its not getting beat like an impact hammer. And I do like case hardening of parts Its really an art and hard to do large areas beautifully. Trigger,actuator buffer switches would be kinda neat. And while its just surface it certainly gets hard. I think Kahr rather than addressing quality control and making a functioning product they ar focused on making Wall hangers. Edited April 18, 2022 by Countryboy77

[Oldtrooper]

The more correct term to use in most cases with this finish would be "Case Colored" Modern steel is sufficiently hard to begin with. Case hardening was used back in the 19th century when many steels were softer, and had a higher level of impurities. Today's case coloring is done chemically in most cases. There are a few guys left who use the old bone and charcoal method, but it is very expensive. If in fact this receiver was case hardened, then machining or filing it is likely not going to happen ... Interesting post.

[Ryo]

Wow.. That is ugly..

 

And why would taking a hammer to a receiver be a good idea.. Most a smart thing to do.

 

BTW is case harden really that hard where you can't even grind a bit off? Even some of my tools I could grind a bit off.

[Tiz]

Wow.. That is ugly..

 

And why would taking a hammer to a receiver be a good idea.. Most a smart thing to do.

 

BTW is case harden really that hard where you can't even grind a bit off? Even some of my tools I could grind a bit off.

Good question. I have never dealt with anything that was case hardened, however you do grind your own tools for a lathe out of HSS which is pretty hard. I would guess that you should be able to grind the case hardened surface of the weapon since it has been pointed out that it is usually only a surface hardening and does not penetrate deeply into the steel.

[Countryboy77]

You can almost always grind some off just depends the tool and bit attachment your using. Im sure Bob is trying to be as careful as possible . Using a hammer to seperate isnt the worst idea New gun dirty gun tight tolerances is understood,but, Use a plastic or rubber hammer or at the very least a piece of wood for a buffer . He did a couple things wrong, didnt protect his piece and hit it too hard .At least it was a Kahr and not a transferrable.

[BRMCII]

Yes, "hardening" is not actually very accurate as it can slightly soften the metal as well in some applications. Depends on the base alloy.
It is really a decorative application in the broad sense.

[Bill DeShivs]

The case hardening can be easily cut through with separating discs or small grindstones. Diamond files will also easily cut it.

[Countryboy77]

I think i would put it in a glass bead cabinet and then a bluing tank.Hell cerakote would look better.Might as well tgrow a red dot and an ar15 monorail on the front with magpul furniture