Machinists, a little advice if you don’t mind.

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new210/22

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Quick background, I bought stainless full stock 10/22 a few years back that had a leupold one piece scope mount on it. Upon receiving the firearm I discovered that it was mounted and held in place in buggered holes by the sheer tenacity of blue locktight. The original #6 holes had been opened up to 8-32. I have since helicoiled the holes and will plug with grub screws. The situation I find myself in is wanting to mount a Williams peep sight but of course I have one of the two mount holes being oversized now.

The question. If I were to secure a 8-32 stainless grub screw with red lock tight and try to drill and tap it for #6-48 am I just going to bugger up the aluminum receiver or does this have a chance of working?

Thanks for your advice.
 
In theory you could make grub screws on the lathe that have a 8-32 thread on the OD and a 6-48 thread on the id like a time-sert.

I would not install it in the receiver before trying to drill and tap it, of its 304 or 316 you are asking for trouble unless you have a mill. I would do it on the lathe before installing it.

If you were to try it with a drill press. Install the screw in a blind hole in scrap metal then drill and the the screw with no risk the the rifle, remove screw install in the receiver hole.

Simplest would be to turn something on the lathe if that's an option. But drilling pre made set screws could easily work too, or even just some threaded rod cut to length then drilled and tapped.

If you found some 416 ss bolts/threaded rod/ set screws/ round bar they would be easy to machine or use a tap and die on.
 
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8-32tpi outside diameter is .164”. Thread depth would be around .127”.
6-48tpi outside diameter is .138-.140”.

.127”-.140”=-0.013” meaning you would be cutting into the threads in the 8-32tpi. You would need to bump up the size of the hole to have enough meat to put a 6-48tpi thread in it.
 
So between the reciever, scope base (or in this case the sight itself) and screws, the cheapest thing to modify are the screws. Turning the head of the screws to suit is the least expensive thing to do (replace) if you screw it up. That being said this is not a drill press job, find someone with a milling machine that knows what they are doing.
 
Eaglelord17 said:
8-32tpi outside diameter is .164”. Thread depth would be around .127”.
6-48tpi outside diameter is .138-.140”.

.127”-.140”=-0.013” meaning you would be cutting into the threads in the 8-32tpi. You would need to bump up the size of the hole to have enough meat to put a 6-48tpi thread in it.
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Good catch, some how I had something backwards and I thought there was 0.013 between the threads
 
Thinking about it more even with the thread over lap you could use filler screws into the receiver and drill and tap them for the screw size you want. I wouldn't used hardened screws though and unless you are used to doing this stuff there is a chance you can mess up the receiver.

Or you could thread the filler screws into a scrap material then drill and tap them, unscrew them, they will look like helicoils, install them into the receiver and be done.
 
Evanguy said:
Thinking about it more even with the thread over lap you could use filler screws into the receiver and drill and tap them for the screw size you want. I wouldn't used hardened screws though and unless you are used to doing this stuff there is a chance you can mess up the receiver.

Or you could thread the filler screws into a scrap material then drill and tap them, unscrew them, they will look like helicoils, install them into the receiver and be done.
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I wouldn't recommend this or even think it is possible. My advise is to have the Holes laser/micro welded closed if there is any of those services in your area and re drill and tap......or.......

Is it possible to just drill and tap new holes in the receiver to mount your new sight?
 
HOSSONE said:
I wouldn't recommend this or even think it is possible. My advise is to have the Holes laser/micro welded closed if there is any of those services in your area and re drill and tap......or.......

Is it possible to just drill and tap new holes in the receiver to mount your new sight?
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Why? And why don't you think it's possible..if I had a 6-48 tap I would make one to show you. It's just a thread adapter. You wouldn't be able to do it without the outer thread having a nut/meteral over it while you taped the id though

I've actually done things many times and have been a manual machinist for 20 years. The op can do it how ever he wants but exactly what he asked or wanted to do would work, I just wouldn't use set/ grub screws because they are often very tough meteral

You could get it welded but that seems a bit much for converting a thread.
 
I was up at the shop working on my hot saw built out of a cr250 engine and decided to try this out. I don't have a 6-48 tap so I didn't tap it but it would take about 40 minutes to make 2 plugs, install and tap.

The method I used shown in the pics of a combo of my original thought and the OP's idea.

First I turn down some steel,
Then thread it 8-32
Then drill it for tap drill size of 6-48 (if there wasn't any thread overlap I would have tapped it in the lathe)
Then part it off
Then install into receiver (I just used a piece of flat bar to mimic the receiver.)
And tap with 6-48

In the last pic I would hit it with a count sink by hand before tapping it 6-48

Doing it this way, there is no shipping costs, no labour/welding costs and takes less then an hour.

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2]
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d]
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[J]
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Eaglelord17 said:
8-32tpi outside diameter is .164”. Thread depth would be around .127”.
6-48tpi outside diameter is .138-.140”.

.127”-.140”=-0.013” meaning you would be cutting into the threads in the 8-32tpi. You would need to bump up the size of the hole to have enough meat to put a 6-48tpi thread in it.
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Did we forget to divide by 2 to get the wall thickness?

.013" difference between major and minor diameter means less than .007" wall thickness.
 
I Dont Care About You said:
Did we forget to divide by 2 to get the wall thickness?

.013" difference between major and minor diameter means less than .007" wall thickness.
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It is -.0065” wall thickness, there is no wall at that size. Considering a 8-32tpi thread only has a thread depth of .0185” that is almost 40% of the thread gone. With no backing to it. Not how I would do it, but to each their own.
 
Why wouldn't you just get #8 screws and modify them to fit in the counterbores of the sight?

Or modify the counterbores in the sight to fit the heads of the #8 screws?

Unless the screw holes have been put in an incorrect location, you would be best off to use them as is.
 
Evanguy said:
^^ the 40% of the threads you say are missing aren't, they would be cut into the minor diameter of the thread in the receiver.
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Evanguy said:
Why? And why don't you think it's possible..if I had a 6-48 tap I would make one to show you. It's just a thread adapter. You wouldn't be able to do it without the outer thread having a nut/meteral over it while you taped the id though

I've actually done things many times and have been a manual machinist for 20 years. The op can do it how ever he wants but exactly what he asked or wanted to do would work, I just wouldn't use set/ grub screws because they are often very tough meteral

You could get it welded but that seems a bit much for converting a thread.
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let me re phrase that. Difficult for someone who is not a machinist. It would be so small and fragile and difficult to lock into the receiver. Also without a quality tap it would likely tear what little material is left.

Just like it’s easy for you to whip that up it’s easy for me to get things laser welded and think it’s easy for everyone. I give them a lot of work so they treat me good and take care of my personal projects with out paper work.

Nice work on that plug.
 
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Look in to the 'other' thread repair inserts, there are a lot out there beside Helicoils. Search for "thread repair inserts" online.

Look at Keenserts and similar. A lot of them use a standard size tap for opening the hole, instead of the Screw Thread Insert (STI) Taps. (the normal tap for a helicoil)

There are actually a LOT of thread repair tools out there, that will make a threaded hole that is as strong, or sometimes stronger than, the original material.
 
new210/22 said:
Quick background, I bought stainless full stock 10/22 a few years back that had a leupold one piece scope mount on it. Upon receiving the firearm I discovered that it was mounted and held in place in buggered holes by the sheer tenacity of blue locktight. The original #6 holes had been opened up to 8-32. I have since helicoiled the holes and will plug with grub screws. The situation I find myself in is wanting to mount a Williams peep sight but of course I have one of the two mount holes being oversized now.

The question. If I were to secure a 8-32 stainless grub screw with red lock tight and try to drill and tap it for #6-48 am I just going to bugger up the aluminum receiver or does this have a chance of working?

Thanks for your advice.
Click to expand...
If it's currently d/t for 8-32, why not just use 8-32 screws on the sight? Why reinvent the wheel? Just my 2 cents. You might have to open up the holes on the sight so that the wider screw will pass though, but that's a super easy job. If the 8-32 screw heads don;t sit flush, it's also a super easy job to countersink.

That's the way I'd go anyway.
 
Canuck65 said:
If it's currently d/t for 8-32, why not just use 8-32 screws on the sight? Why reinvent the wheel? Just my 2 cents. You might have to open up the holes on the sight so that the wider screw will pass though, but that's a super easy job. If the 8-32 screw heads don;t sit flush, it's also a super easy job to countersink.

That's the way I'd go anyway.
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I considered that. The peep sight was nice enough I didn’t want to mangle the finish, to keep the repair hidden. I ended up using a different reciever I had laying around that polished up better than I expected it would.
 
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