Snidely70431
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- Mar 10, 2018
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Excerpted from Clyde Baker's "Modern Gunsmithing". Copyright 1931
Mark where the barrel is to be cut and cut it about 1/32" ahead of the mark. Set the barrel upright in a vice and dress the muzzle flat and as nearly square as possible with a sharp mill file. Do not worry if it is not perfectly square. The bore will be square when the lapping operation is finished.
Using a countersink reamer, countersink the edge of the bore about 1/32" to get rid of excess metal and hasten lapping.
Secure 4 brass balls measuring respectively 3/8", 1/2" 5/8" and 3/4". Drill each ball about half way through each ball and tap for 8 x 32 screw, which should be turned in tightly. Cut the head off and use the screw for a shank.
Chuck the smallest ball in a breast drill or brace, put on a small quantity of valve grinding compound and lap the ball into the muzzle, the lapping the inner edge of the bore. Continue with the next largest ball in the same manner, then the two larger sizes until the inner half of the barrel wall is well rounded. Round off the outer edge of the barrel to a corresponding shape with a file then polish the edge.
A muzzle lapped in this manner must be square. The surface of a sphere will not touch the edge of a cylinder at all points until their axes coincide, that is, until the end of the cylinder is square.
Do not crown a muzzle too deeply. Leave the edge sharply defined.
Mark where the barrel is to be cut and cut it about 1/32" ahead of the mark. Set the barrel upright in a vice and dress the muzzle flat and as nearly square as possible with a sharp mill file. Do not worry if it is not perfectly square. The bore will be square when the lapping operation is finished.
Using a countersink reamer, countersink the edge of the bore about 1/32" to get rid of excess metal and hasten lapping.
Secure 4 brass balls measuring respectively 3/8", 1/2" 5/8" and 3/4". Drill each ball about half way through each ball and tap for 8 x 32 screw, which should be turned in tightly. Cut the head off and use the screw for a shank.
Chuck the smallest ball in a breast drill or brace, put on a small quantity of valve grinding compound and lap the ball into the muzzle, the lapping the inner edge of the bore. Continue with the next largest ball in the same manner, then the two larger sizes until the inner half of the barrel wall is well rounded. Round off the outer edge of the barrel to a corresponding shape with a file then polish the edge.
A muzzle lapped in this manner must be square. The surface of a sphere will not touch the edge of a cylinder at all points until their axes coincide, that is, until the end of the cylinder is square.
Do not crown a muzzle too deeply. Leave the edge sharply defined.
