Corbin Bore Lap, 54-lb pail (6-gal)
	Quantity in Basket: None Catalog No.: CBL-54 Price: $1,195.00 Shipping Weight: 54.00 pounds
	Optional Note:
	Quantity:
This is a 54-lb 6-gallon pail of Corbin Bore Lap, as used for production of top quality rifle barrels. This can be shipped by UPS in the USA, or by UPS international to other countries where permitted. The lapping compound is an oil based suspension of synthetic sapphire in a proprietary flat structure, with a particle size distribution that peaks at 40 microns. Under the pressure of a lap, the crystals try to squeeze into the smallest possible space, which would be primarily parallel to the bore. Moving the tight lap back and forth in the bore makes the edges of the crystals impact anything that projects from the bore, while the flat sides of the crystals slide along the surface without presenting a cutting edge to it. This takes out tool marks, fouling, impacted copper or molybdenum disulphide, rust or anything else that is softer than sapphire, and sticks out from the bore surface. But it minimizes actual bore size wear once the high points are smoothed out. Bear in mind that when you measure a hole diameter accurately, your measuring instrument probably is reading across the highest points at that particular position. So if you remove the highest points, be they tool mark edges and burrs or foreign matter, the bore will appear to be larger diameter on a second measurement, even if the main or average surface to surface diameter is not changed. When we lap bullet swaging dies and hold about 50 millionths tolerances in their bores, we are taking out the high points from machining and reaming to get to the underlying surface. Lapping cannot "fill in" gouges or cuts that go below the median surface diameter, but it can take out the peaks that project above it. So you can still have grooves in a surface after smoothing it by lapping. There are two ways to remove scratches or grooves in the median surface level. One is to remove the entire surface area that is higher than the bottom of the deepest groove, which of course will enlarge the diameter by that amount (or technically twice the amount of the deepest groove since you take it out "all around" and not just on the one side where the groove may be). The other is to put something into the bore that will fill in these low spots and bring them up to the median level. Fouling tends to do that by itself, but it generally promotes corrosion and rusting because it is a different metal and will cause electrolysis in the presence of moisture, or because it may trap corrosive materials or moisture under or in its more or less porous surface. Using an inert filler such as Molybdenum Disulphide or Tungsten Disulphide can fill in the low areas with something that does not promote corrosion and sticks well enough not to allow anything to become trapped under it. But some gunsmiths have reported excessive build-up of moly that can itself become a projection or tend to round out the corners of rifling grooves, and it is nearly impossible to remove with lead and powder solvents. Bore Lap (and the more mild action of Corbin Bore Cleaner, 15 micron particle size) does not rely on chemical reaction, but mechanically slices away projecting bumps and lumps. Gunsmiths report that it removes excess moly and in those instances can restore accuracy. Do not use Corbin Bore Lap as a regular bore cleaner! It is a good thing for rusted, severely fouled, or brand new barrels that could benefit from a little tool-mark removal. But it will wear down rifling if used on a regular basis instead of a proper cleaner. To remove Corbin Bore Lap from the bore after lapping, use a cloth patch wrapped on an old brass brush, and a good grade of gun oil such as Corbin's FSO-16 (Five Star Oil, an ISO-15 non-gumming instrument and gun oil, similar to lathe spindle oil).