Ethnographic Arms & Armour - View Single Post

Philip · 11th August 2010, 07:55 AM

A great book to have is Ronald Lister's ANTIQUE FIREARMS: THEIR CARE, REPAIR, AND RESTORATION (NY: Crown Publishers 1963). There's nothing quite like it and it's a godsend. Unfortunately I don't think it's been reprinted. The author is British so copies may be more common, in the antiquarian book market, in the UK.

Based on info in the book, here's a suggestion on extracting that stuck copper brush. Find a long thin-walled metal tube just smaller than the bore, and of sufficient length to reach the obstruction and still allow a hand grip. Drill a transverse hole in one end, enough for a short metal rod to serve as a turning- and pulling-handle. On the business end, file four V-shaped notches on the periphery of the tube. Then make four small L-shaped cuts with a wire-saw or similar device at the bottom of each V. If you push the rod into the barrel and engage the bristles of the brush in the saw-kerfs in the tube, you might get enough of a grip on the thing as you slowly rotate and gently pull on the tube.

Now, on to the malfunctioning lock. What you have is severe wear on the tumbler notches and the sear nose. The full-cock notch needs to be carefully filed so that it has a square "step", not the rounded hump that's there now. The sear nose must also be shaped to mate with this indent precisely (carefully note the position of the two components when the lock is in a full cock position, to guide you in making the angles in the detent and on the nose just so.). The half-cock notch needs to be undercut slightly to allow the sear nose to lock into it. (there is a diagram on p. 150 of Lister's book).

If the hammer catches on the half cock detent as it falls, it means that the radius of the tumbler is worn out-of-true. Try and correct the sear nose and the full cock detent first, then work on the half-cock. By restoring the full undercut in the half-cock detent, you'll be filing the radius of the tumbler a bit smaller in the area between full and half cock (i.e., setting the radius closer to the axis-pin.) You can then dress down the radius below the half cock, reducing the diameter of the tumbler at that point (but not so far so as to compromise the undercut). This adjustment of the radius is usually enough to cure the "half cock grab" syndrome.

You might also want to be sure that the mainspring and tumbler move with out undue friction against the lockplate, or against the tumbler bridle. Minimize friction and the lock becomes "faster" and that helps prevent half-cock grab, too.

11th August 2010, 07:55 AM	#11
Philip Member Join Date: Dec 2004 Location: California Posts: 1,036	two possible fixes: bore and lock A great book to have is Ronald Lister's ANTIQUE FIREARMS: THEIR CARE, REPAIR, AND RESTORATION (NY: Crown Publishers 1963). There's nothing quite like it and it's a godsend. Unfortunately I don't think it's been reprinted. The author is British so copies may be more common, in the antiquarian book market, in the UK. Based on info in the book, here's a suggestion on extracting that stuck copper brush. Find a long thin-walled metal tube just smaller than the bore, and of sufficient length to reach the obstruction and still allow a hand grip. Drill a transverse hole in one end, enough for a short metal rod to serve as a turning- and pulling-handle. On the business end, file four V-shaped notches on the periphery of the tube. Then make four small L-shaped cuts with a wire-saw or similar device at the bottom of each V. If you push the rod into the barrel and engage the bristles of the brush in the saw-kerfs in the tube, you might get enough of a grip on the thing as you slowly rotate and gently pull on the tube. Now, on to the malfunctioning lock. What you have is severe wear on the tumbler notches and the sear nose. The full-cock notch needs to be carefully filed so that it has a square "step", not the rounded hump that's there now. The sear nose must also be shaped to mate with this indent precisely (carefully note the position of the two components when the lock is in a full cock position, to guide you in making the angles in the detent and on the nose just so.). The half-cock notch needs to be undercut slightly to allow the sear nose to lock into it. (there is a diagram on p. 150 of Lister's book). If the hammer catches on the half cock detent as it falls, it means that the radius of the tumbler is worn out-of-true. Try and correct the sear nose and the full cock detent first, then work on the half-cock. By restoring the full undercut in the half-cock detent, you'll be filing the radius of the tumbler a bit smaller in the area between full and half cock (i.e., setting the radius closer to the axis-pin.) You can then dress down the radius below the half cock, reducing the diameter of the tumbler at that point (but not so far so as to compromise the undercut). This adjustment of the radius is usually enough to cure the "half cock grab" syndrome. You might also want to be sure that the mainspring and tumbler move with out undue friction against the lockplate, or against the tumbler bridle. Minimize friction and the lock becomes "faster" and that helps prevent half-cock grab, too.