1911 Pin hardness

[redlightrich]

Hi all, I am in the process of putting a pin in the slide stop notch on an aluminum 1911/22 slide. It is a conversion slide, that I want to allow to lock back by changing the magazines.
My question is what hardness of pin should i use, I don't want to go so hard that is breaks.
Nelson custom guns uses a pin in their slide stop notch, on an aluminum slide with great results. I want to do a similar thing, but am wondering which hardness is ok. Or am I overthinking this? Is any steel pin better than the aluminum?
Any input would be greatly appreciated

[Jim Watson]

I have thought about that, too.
My Nelson is good.
My SM ACE is not. The stop notch peened out, steel on steel. I had it welded and recut but it did not last.
A pin might be a better fix on mine, too.
The shank of the drill would probably work as well as anything.

[HiBC]

It happens that gunsmithing projects sometimes require hard and tough pins.
Here are some options.
Its been over 20 years since I was working on molds,so his info may be a bit rusty.....but searching will work for you.

Standard dowel pins: Tough core.I don't know what steel. Surface hardened quite hard. Not real machinable . OD ground typically a couple of tenths of a thousandth oversize for a light press fit with nominal reamers.

There is a mold supply house called DME . You might also find this stuff at MSC.
Mold ejector pins : Typically H-13 tool steel. Typically nitrided for and tough surface (Someplace in the 50s Rockwell "C") Sorry,I'm writing this from recall.
These have a head on them . Typically od ground .0004 to .0007 under nominal diameter.

Mold core pins I think these are also H-13 hotwork tool steel. There are two hardnesses. As I recall,MX and CX pins. I forget which is which but one is about as hard as you can machine easily with high speed cutters and the other requires carbide or grinding.
These also have a head on them. I've made a few 1911 reverse plugs from these.

For what you get and the time and trouble they save, they are a bargain.

You might look a ejector sleeves and blades,too,if you are in the catalogue.

[redlightrich]

Thank you for the replies. I thought of taking the shank off a drill bit and making a "dowel" but was afraid it was too hard. I believe HSS is about 50, Caspian claims their slides are 38-42 RC. Now that is the entire slide. I am just talking about a pin.
Keep in mind, the recoil spring is only around 6# so the impact would be weaker than a .45 with a 16#.
My questions become, will a soft pin RC16 peen too easily?
Will a hard pin RC58-60 shatter? I only have room for a pin which will be approx .0615-.0625, and even that small I have very little margin.

If I use a soft pin, and it fails, I can probably replace it.
If i use a hard pin, and it fails, It may be very hard to remove/replace.

Thank you

[HiBC]

I avoid putting blind pins in as a general rule.

I don't know what it is you are going to do. For that small of a diameter a standard surface hardened dowel pin would not peen and they are tough.
But if a dowel is pressed in a blind hole it does not come out easy.

Example the hole for the pin that holds the ejector in is drilled through both sides of the frame.A punch can be used to drive the pin through.

[Aguila Blanca]

Originally Posted by HiBC

I avoid putting blind pins in as a general rule.

I don't know what it is you are going to do. For that small of a diameter a standard surface hardened dowel pin would not peen and they are tough.
But if a dowel is pressed in a blind hole it does not come out easy.

Example the hole for the pin that holds the ejector in is drilled through both sides of the frame.A punch can be used to drive the pin through.

Hmmm ...

Where does Nelson put this pin? Looking at images on Nelson conversions, I don't see a pin on the outside face of the slide. That suggests to me that the pin may/must be drilled into the face of the recess. If that's the case, it will have to be a blind hole.

https://external-content.duckduckgo....25d&ipo=images

[tangolima]

Spring stock is my go-to type of steel for guns. Looks like in the picture the steel pin is imbedded in the notch to bear on the catch. It avoids bearing on the soft aluminum. Makes sense.

I suppose the hole is already there, or it is to be drilled. I would cut some circular grooves on the pin as anchors. Degrease the hole and pin. Epoxy the pin in the hole. When the glue cured, the pin is fitted if needed.

Other option could be better actually. I would tap the hole. The pin is a stainless steel screw. Loctite and fitting.

-TL

Sent from my SM-N960U using Tapatalk

[Unclenick]

Redlightrich,

What changes with hardness is the yield point of the steel, which gets higher with hardness, and the elongation at break, which gets shorter and is responsible for brittleness. However, the modulus of elasticity, the amount of applied force that deforms the steel a certain amount, is the same. In other words, if you have a pin hard enough that it doesn't peen into a different shape in your application, then it doesn't deflect or bend any more or less under your applied force than harder pins do. Just as long as you are staying clear of the failure points, any pin hardness in that range will have the same effect on your aluminum.

Ideally, you want something hard enough to avoid deforming but not hard enough to be brittle and shatter. Steel with the hardness of the head of a hammer is a good choice for this duty, where it takes a pounding. Unless you are going to get into the expensive air-hardening high chromium steels used in impact forming dies, something like O-1 oil hardening drill rod heated and quenched and then drawn back in an oven at about 800°F will give you a Rockwell C scale hardness of about 48-50, and that's a good range for a hammerhead. Commercial centerless ground dowel pins often have a core like that but a surface that is closer to Rockwell 60 via flame hardening or carburizing. This is sort of like a Japanese sword, with a hard exterior supported by a softer core that can take impact without shattering. So a dowel pin the right size would be a good idea.

[redlightrich]

Thank you all so very much. I will use a dowel pin, with RC of 58 or so.. To answer question about where Nelson puts the pin, it is at the rear portion of the slide stop notch, It is perfectly positioned so the pin is protruding out side of the aluminum slide, so as viewed from the bottom you can see it.
It is indeed a blind hole, which isn't ideal, but we are faced with constraints.
the lower portion of Nelsons pin hole is about 270 degrees ( the rest of the aluminum is removed in the boring process) for the depth of the slide stop notch, but above that, into the slide, the pin is encased 360 degrees. I can't tell how deep the hole is, but I would imagine near .375, which is the depth I will use for strength.

Wish me luck!!

[redlightrich]

Hello again, Hey, TL, you gave me a good idea. I can also use a #0 set screw, which will allow me to remove in the future if necessary.
A "0" size set screw is about the same size as a 1/16 dowel pin. I may even have the correct tap on hand.

Thanks again

Rich

[tangolima]

Originally Posted by redlightrich

Hello again, Hey, TL, you gave me a good idea. I can also use a #0 set screw, which will allow me to remove in the future if necessary.

A "0" size set screw is about the same size as a 1/16 dowel pin. I may even have the correct tap on hand.



Thanks again



Rich

Yeah but you still need to fit and file away the screw threads on the bearing face, or it will catch the catch (what a mouthful!).

-TL

Sent from my SM-N960U using Tapatalk

[redlightrich]

UPDATE:
After thinking this thru a few times, I had decided it may be best to go with a blind hole, and a hardened pin.
I did like the idea of using a set screw, because of it's ability to be removed, and a size "0" would have worked, however, I was afraid that after tapping it, the threads would create stress risers that after continued impact may start cracks.
Anyway, the hardened pin has been installed. I will report back on how it holds up.

Thank you all for your insight and input,

Rich

[tangolima]

Nothing wrong. Did you press / epoxy the pin in place?

-TL

Sent from my SM-N960U using Tapatalk

[redlightrich]

I wound up with a light press fit. Approx .001, and I used red loctite for assurance. I will run a few hundred rounds this weekend and get an idea as to how effective it is.

I will report back

Ty

Rich