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Broken screw on target rifle barrel

XM21

Plastic
Joined
May 8, 2013
Location
Ohio
I have an old Anschutz target rifle with a broken screw on the front sight block hole. Broke flush so nothing to grab onto. It is pretty small, 6-40 (or metric) I'm thinking left hand drill might get it out.?
 
Not sure I would trust a drill to track straight. Small end mill, maybe. Left-hand is a good approach, regardless. A square easy-out that small might be hard to find, but worth a search. The spiral ones tend to tighten the fit as they go in, but you can control the square ones' distortion better.

If you 'mill good', you can pick out the thread leftovers with a dental pic and you're good to go.
 
Not sure I would trust a drill to track straight. Small end mill, maybe. Left-hand is a good approach, regardless. A square easy-out that small might be hard to find, but worth a search. The spiral ones tend to tighten the fit as they go in, but you can control the square ones' distortion better.

If you 'mill good', you can pick out the thread leftovers with a dental pic and you're good to go.

What size end mill would one use to mill out a #6 screw? I would worry about breaking the cutting tool.
 
I had to remove a few broken (flush or below) 6-32 screws and this is what worked for me with what I had available. First thing was I put some good penetrating oil on the screw and let it work. This is ALWAYS the first thing I do with stubborn mating parts. I set the part up in the mill and aligned the holes as close as I could. Then, I just touched the top of the screws with an end mill to make a flat spot on top. Next, center drill a dimple and drill a hole (don't remember what size exactly, but small enough so I know I wasn't going outside the minor diameter of the screw). Then, I hand ground a tapered square easy out from a piece of 1/8" square HSS tool bit. Grind to fit, but leave it as big as you can for strength. Tap it in and try working the screw out working it in both directions if needed/possible. I got the 3 or 4 out this way on my project and it might just work for someone else as well.

Good luck,
Ted
 
Good to find out what thread it might be...perhaps the other hole for depth is held with btwo screws.
we had good luck drilleing to depth with a drill a bit smaller than the minor diameter with a left hand drill so the stuck will come up amd out..but a valuable gun best done by a gun smith.
Tap Chart UNC/UNF Threads - provides tap sizes, drill sizes, pitch, (threads per inch) basic major diameter, basic effective diameter, basic minor diameter of external threads, and basic minor diameter of internal threads for UNC/UNF threads
 
If the screw was broken without being bottomed and is actually loose in the hole an air powered engraver will often walk the screw out quickly. Electrics need not apply.
 
Screw should be 6-48. Got a milling machine? If so just use a small center drill to drill into the center of it and drill it out with a drill just a little smaller than the tap drill size then get a 6-48 tap and work on it from there. I have a few ans target rifles and I think I still have an older one with the front block. I can check the screw size if you want to make sure but I am pretty sure it is 6-48.
 
If it is 6-48.. like Pete said center drill then perhaps a 3/32 drill and drill .094 to .098 or so to near through or through then a square easy out...for a tap drill #31 (.120)

but do be sure of every thing ..That is a nice gun to not mess up..
 
If the screw was broken without being bottomed and is actually loose in the hole an air powered engraver will often walk the screw out quickly. Electrics need not apply.
That's what I was thinking. It's easy to assume the screw is stuck when it's not.

I've removed screws with broken heads with a pick. Just find a spot on the break to hook onto, and unscrew it. There's usually a spot on the break that sticks up a little.

Always the first thing to try...
 
A lot of good suggestions already about getting it moving with an engraver or punch. Left hand tools were mentioned but are hard to come by in the size you need. An easy way to make one will be to take an appropriate size center drill with a dull tip and resharpen it by hand to a left hand cut. This will just be the pilot not the 60 degree portion. A #1 would work and maybe a #2 if you are careful.
 
When I have been faced with similar problems, I try the punch and small hammer to see if the screw will unscrew that way first. If not, I center punch the broken end of the screw as near to center as I can. I then drill with a small drill, like a number 60 and follow with slightly larger drills until I can see how far off or close to center I am. If off center, I switch to a small dental burr and remove material from the thick side until the hole looks closer to being centered. Back to a larger drill bit until I am near in size to the the 6-40 tap drill and check for concentricity. If it looks good, drill it one size smaller than the 6-40 tap drill. At this point you should be able to pick out the remains of the screw. I use a reversible flex shaft tool and sometimes running in reverse with the dental burr will unscrew it as well.
 








 
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