remove remnants of nipple

[rudyc]

I had to drill out a frozen nipple from a double shotgun. Tried all types of penetrating oil and heat combinations for 2 weeks, no go. I have it drilled out just to where the threads start showing.  My question is this: how do I proceed from here? What is a good method of clearing out the threads? The sister nipple is a .020 oversize 1/4-28. The drilled out hole mikes at .250 Should I just get an oversize tap and re-tap the hole?

thanks,

rudyc

[coutios]

  Good Morning RudyC.. Hold off with the tap just yet. First continue to apply the penetrating oil now that you have some of the threads exposed. I have had some good sucess with using a scribe to gently pick the remaining thread out. Go easy and it should begin to lift out in sections just like a coil spring now that the centers gone.. Then carefully retap not forgetting to use a cutting oil...Keep us posted...Good luck..

Regards
Dave

[RonT]

Yes...tread lightly.  I used a bent needle and then my thread pitch gauge to "pick" out remnants.  Think "chase" rather than "tap" when you do use your tap.  JMHO.
R

[oldiemkr]

I agree with coutios.

I just got one out that was extremely hard metal. Couldn't touch it with a HSS drill.

Drilled it out with carbide then picked it put with a scriber. It takes awhile but when its out your done.

If you have a small needle file you can cut a SMALL groove down one side and pick from that groove. SMALL grove ! Maybe just the top two threads.

[doug]

     I have replace a number of nipples on original shotgun.  Usually once you have the remnants of the old nipple out, the threads in the breach need chasing out to get to solid metal.  That means making one or a series of taps of the same pitch as the nipple and increasing in diameter by .005 to .010" each time.  Essentially cut a screw thread to the diameter you want, harden spinning and cut flutes for the chips using a cutting wheel on a dremel tool.  It also means making new nipples with threads to match the new threads.
    Most english shotguns used 26 threads per inch by the way, at least in my experience

cheers Doug

[rudyc]

Well, success has reared it's ugly head!!

The threads are now cleared out and a replacement nipple fits great.

I took the above advice and just soaked the remaining nipple part and picked away at it for a couple of days with a scribe.  Today the threads are clear and the gun is shooting. 

Many thanks for all that posted their advice.

rudyc

[coutios]

   Don't ya just love it when a plan comes together?.......

Regards
Dave