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In the photo above where I am holding the shoe lump platform into the machined recess of the prototype barrel breech end, you can see the extractor hole clearly. As you would expect the extractor hole must be drilled precisely for the full length of the shoe lump platform. Such a precise hole is outside the realm of typical drill press drilling. A "D" drill is made to drill using drill rod and milling the "D" section at the end of this shop made "D" drill. After you make the "D" drill you must hardened it and temper it back with only about 350 degrees F temper. Some of you will have not encountered a "D" drill or the technique of using them. If you will Google "how to make and use a "D" drill you will find all about them and so forth.

In order to start the hole with 100% accuracy a ball tip milling cuter of the diameter required is used and the depth of the hole is cut with the milling cutter to about 1/2 inch. Then you complete the drilling with the "D" drill, WHICH is long process as you only drill a depth of .050", back the "D" drill out of the hole, clean the hole of all chips and continue on at increments of .050" per drilling cut. The position of the milling machine that you are using to do the drilling as well as the milling vise and table must not be changed during the entire process, which is likely to be more than one hour.

Although a photo of "D" drilling is above (photo #6 from the start of the post). I am adding it here again. I cannot over emphasis how important a hole through the shoe lump platform that does not deviate more than +/- .005" from end to end is in order that an automatic ejector system works properly. If you do not get this done properly, then you are in for trouble later on on a set of barrels that have been brazed to the shoe lump, and the hole cannot be re-drilled to correct the problem. If you do not have it drilled properly, then discard the shoe lump platform and make a new one and drill it correctly. Gunsmiths who have had experience in drilling such accurate holes in making a set of barrels are seldom found, and practice is required before they do this work. Engravers practice engraving an entire side lock or whatever they are working on before we actually do the engraving on the gun or rifle. This practice may take many hours or days, but you cannot afford to "mess" up a gun or rifle and set yourself for days of work that you will not receive compensation.

Notice how early in the shoe lump platform machining that I have "D" drilled the extractor hole (7/32"). If you delay drilling this hole and you drill it off, then you will have maybe 1/2-1 day of work that you will have to discard.

Edited by CptCurl (06/05/17 09:41 PM)

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