Have a commerical receiver with 6/48 scope holes that need to be increased in size. The receiver is very hard and almost a purple color. Have enlargened holes with a carbide reamer on mill however can't tap. It's been suggested that the area around the holes be spot annealed so they can be tapped. How do the pro's do this? What color do you heat to and do you need to reharden? Advice greatly appreciated. Ron

You might consider hiring that part out to a gunsmith who is knowledgeable in this type of work. Maybe save doing your own or other peoples receivers until you can gain some experience through practice on old discarded and destroyed actions. Unless you have someone by your side to talk and guide you through it, I wouldn't recommend it as a first time project. Too easy to screw up.

One method is to heat a 1/4" dia rod to red heat and press against the hole while it cools. Another method is to polish the inside of the hole until colors will be visible and then heat with a pinpoint torch flame until the color changes to blue. Then tap, using plenty of fluid.

Do not attempt to re-heat-treat!
Regards, Joe

quote:

You might consider hiring that part out to a gunsmith who is knowledgeable in this type of work. Maybe save doing your own or other peoples receivers until you can gain some experience through practice on old discarded and destroyed actions. Unless you have someone by your side to talk and guide you through it, I wouldn't recommend it as a first time project. Too easy to screw up.

this is some of the best advise your are ever going to get

I am a little surprised at the lack of response to this. It seemed like a pretty simple question, asked on a gunsmithing forum...

"Hire a gunsmith" doesn't really fit with the spirit of this board. I didn't see RGG_7 state that is was his first project. He has a mill, that presumes some level of experience in metal work. And even if it was his first, you gotta to start somewhere.

D&Ting a receiver isn't rocket science - I did my own on my first project using a B-Square jig and the results were just fine without anybody by my side to "guide me through it".

I didn't have to spot anneal first, but I'd like to hear more of what the pro 'smiths have to say about it. (thanks for your post JD!)

Westpac, Butchloc, are either of you gunsmiths? Do you know more background about the poster that isn't evident in his question? I'm just curious what lead both of you to conclude that RGG_7 is incapable of performing this relatively simple task. What specific aspect of it requires the expertise of a formally trained gunsmith?

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Originally posted by montea6b:
Westpac, Butchloc, are either of you gunsmiths?

Nope.

quote:

Originally posted by Westpac:

quote:

Originally posted by montea6b:
Westpac, Butchloc, are either of you gunsmiths?

Nope.

Thanks. And there was nothing derogatory in the question, I just didn't know. I am a do-it-yourselfer, sometimes to a fault. I like to read the advice given by experienced pros to those (like me) attempting their own projects. Often in these threads one can sense when somebody is getting in over their head, and if they don't realize it themselves, it helps to be reminded when the time is right to farm out the work. I didn't see it in this case and wasn't sure if there was previous history in RGG_7's posts that I wasn't aware of.

Semper Fi.

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Originally posted by montea6b:

quote:

Originally posted by Westpac:

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Originally posted by montea6b:
Westpac, Butchloc, are either of you gunsmiths?

Nope.

I like to read the advice given by experienced pros to those (like me) attempting their own projects. Often in these threads one can sense when somebody is getting in over their head, and if they don't realize it themselves, it helps to be reminded when the time is right to farm out the work.

Oh, you mean like when someone with a milling machine wants to heat critical parts of a receiver to draw down the temper so they can drill and tap it? What if an experienced pro told him the same thing, would that be more credible than one of us regular guy's?

And Semper fi!

Spot annealing is fairly simple if one remembers a few caveats. In order to soften the steel enough for tapping, it must be heated to draw down the hardness IN THAT SMALL AREA without also softening the steel around it.

If not heated enough then it'll remain too hard, and if heated too much then it'll also remain too hard!

This seeming paradox is the key to the softening procedure. The steel's temp in the tiny area of the hole must be raised to at least 600F but not more than about 1200F, and it MUST be allowed to cool slowly. 600F is a blue color and is about the least amount of heat that would make any difference. 1200F is a dull red and is TOO HOT unless allowed to cool VERY VERY slowly indeed.

The problem lies in the quenching action of the surrounding cooler steel. If the tiny heated area is not prevented from cooling too fast, the bulk of the surrounding steel will act as a heat sink and suck the residual heat right out of the heated area, thus quenching it back into hardness again. This is the reason for holding the red-hot 1/4" rod against the hole until it cools, the hot rod will prevent the abrupt quench. Maynard Buehler used to recommend a 1/2" steel cube for this purpose, he heated it red and balanced it on top of the hole's entrance until it cooled. The relatively small volume of red-hot steel will limit the softening action to the small area surrounding the hole.

IMO it's very beneficial for the client to know at least the bare bones of the proper procedures himself, even if he's not mechanically inclined. By knowing the RIGHT way to do something and the reasons for it, he can better judge if the 'gunsmith' is really competent or not.
Regards, Joe

I don't remember the details, but there are more than a few ways to spot anneal described in the Brownells Kinks books. One I actually used many, many years ago involved using the carbon core from a then standard flashlight battery and a 12 volt car battery. Hooked up the wires and used the carbon core rod touched to the hole. Did the trick and did not harm the bluing.

I think Westpac was looking ahead to the possible DIY problems. Let's say our hero fires up the torch and tries to spot anneal...JD Steele is right on the button...you can easily reharden.

Now suppose he tries to drill...drill squeals like hell, but he gets thru "Must be annealed"

So..he winds in a tap..."snap" Now he's got a stuck tap to deal with.

You see where I'm going with this? I've had to remove LOTS of broken taps with this very history.

There are many ways to spot anneal. Maynard Buehler suggested you heat a piece of steel red hot (about 1/2" square, try to rough contour the bottom) Set it on the receiver, cover up with asbestos (These days kitty litter will work) and let it soak until completely cooled off. I like to take the chill off the receiver beforehand.

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Originally posted by Duane Wiebe:
I think Westpac was looking ahead to the possible DIY problems.

That's my job.

This is not DIY but I can cut your threads with EDM....
If you need it shoot me a PM...time and material.

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Originally posted by Westpac:

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Originally posted by Duane Wiebe:
I think Westpac was looking ahead to the possible DIY problems.

That's my job.

I know where Westpac is coming from, he and I had a few PMs on the side. Thanks Malm.

My main thing is that I like to see these techniques and potential pitfalls discussed openly so we can all learn something. I don't like to see the quest for knowledge being squelched.

Joe says it best here:

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IMO it's very beneficial for the client to know at least the bare bones of the proper procedures himself, even if he's not mechanically inclined. By knowing the RIGHT way to do something and the reasons for it, he can better judge if the 'gunsmith' is really competent or not.

Now, instead of RGG_7 going off on his own and getting a couple local opinions, having the work done, and the rest of us amateur hobbiests being in the dark, we have several experienced professional gunsmiths putting out information that we can all benefit from. (even the less experienced pros may pick up a couple tips...)

That's why this forum is so great!

well with 20 or so guys working in the inhouse back shop i'd hate to count the number of time a day (yes a day) that we have to fix up things that someone that didn't know what they were doing tried it anyway. and when it comes to knocking back temper or putting it back it can be a bit tricky. incidently we figured it out a few years back & we spent about 10,000 hrs a year fixing boo boos

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What if an experienced pro told him the same thing, would that be more credible than one of us regular guy's?

OK, I answered this privately after Westpac reminded me of his credentials, but I can't just let it go...

Yes! Real word experience trumps book smarts every time when it comes to credibility.

There are some very smart "clients" that post here whose opinions I respect, but it is after all a GUNSMITHING forum, and I will defer almost every time to a guy who does this for a living.

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Originally posted by butchloc:
incidently we figured it out a few years back & we spent about 10,000 hrs a year fixing boo boos

Hey, that's good business!

Thats almost 5 full-time employees doing just re-work/repair......sounds like the shop I work for.

I have 2 primary purposes for being here on this site, the first is to learn and the second is to inform. I think many if not most of us are here for the same reasons, so why not inform whenever we can? In my case it's a way to pay forward some of the past favors done me by various mentors as well as for me to learn new ways of doing things.

IMO a person who is reluctant to freely share knowledge with others is probably also a person whose knowledge base is very limited, probably too limited to be of much value. I've found that, like Paul Simon says in the song, there are usually about 50 ways to do any particular thing. IOW it probably ain't no big secret so flop it out there on the forum so we can talk about it!

Some ways are easier than others, and I want to find out the EASIEST!
Regards, Joe

quote:

Originally posted by Mike in Michigan:
I don't remember the details, but there are more than a few ways to spot anneal described in the Brownells Kinks books. One I actually used many, many years ago involved using the carbon core from a then standard flashlight battery and a 12 volt car battery. Hooked up the wires and used the carbon core rod touched to the hole. Did the trick and did not harm the bluing.

Mike,

I had read that somewhere, and was going to mention it, but you made the posting.
Maybe Roy Dunlap mentioned it, I don't recall.

Don

I believe the car battery method of annealing was by Vickery. I remember seeing it in one of my books. My copy of Vickery is missing (I think one of my brothers pinched it) and none of my others mention the method (Dunlap, MacFarland, Howe, etc.).

Jerry Liles