Much of gunsmithing is detail work, and abrasive stones are the proper tool for polishing and shaping metal parts. Stones also sharpen and maintain the variety of cutting tools used in day-to-day gunsmithing. You will need a selection of different sizes, shapes and grits.
   There are several different types of stones you can use. The first are natural stones. Most are silicon quartz, which are mined primarily in Arkansas and are usually called Arkansas stones. They tend to polish as they sharpen, and for edged tools they remove less metal than man-made stones when sharpening. This feature is also very beneficial for working on triggers, as the idea is to polish the engagement surfaces rather than reshape them or remove metal.
   These stones are mined from the earth and processed. There are several grades, but no true industry-wide set standard. Norton may well be the largest supplier of abrasive stones and it uses its own grading system for natural stones, which is as follows: Norton Soft Arkansas; this is an extra-fine stone, but is still the coarsest-grained of the Arkansas stones. Next is the Norton Hard Arkansas. The company rates this as “super-fine” but states that it’s less dense than a hard Arkansas stone. Finally, it has a Norton Hard Translucent Arkansas. This stone is rated ultra fine and is used for the finest finish. It would be a good choice for trigger work and the like where the task is polishing critical areas.
   Next are man-made stones. These are manufactured stones and can be made from several different materials. Norton calls its aluminum oxide stones “India stone.” They have very hard, smooth cutting edges for close tolerance and are the best choice for most gun work other than polishing.
They are usually orange in color and are offered in coarse, medium or fine and a wide variety of shapes and sizes. Cross sections include flat, round, square, triangle, tapered, knife edge and more. In fact, there are almost an infinite number of shapes and sizes.
   Silicon carbide stones are also man-made and they are fast-cutting stones, but do not give as nice a finish as the aluminum oxide stones. Silicon carbide stones are fine for removing material or sharpening tools, but not for polishing parts. Usually they are used in a bench stone. Again, they are offered in coarse, medium and fine.
   Finally there are ceramic stones. These are also man-made and are less expensive than natural stones. They can produce a very fine finish and are very precise. They resist wear and retain their precise angles and shape well.
   They work well for a lot of different applications, but are excellent for precise polishing work, such as trigger sears. Ceramic stones do not require oil during use as with the other man-made and natural stones and can be used dry or with water. This makes cleanup easier. When they glaze over they can be cleaned with scrubbing powder and water. Also, because they can be used without oil, they eliminate the risk of oil contamination when sharpening tools used on fine wood stocks.
   Water stones are man-made stones used primarily for sharpening woodworking tools. They are named this because they use water rather than oil and so reduce the risk of staining a fine wooden stock with oil transferred from a stone by the tools.
   However, they are soft and wear out quickly. They often require “dressing” to keep them flat. There are other stones designed for doing this dressing chore. If you are working with fine walnut stocks, a water stone that is dedicated to sharpening your carving tools is a very good idea.
   Finally we have diamond stones. These stones feature multiple layers of micron-sized monocrystalline diamonds, the hardest material known to man. The diamond “chips” are bonded to a metal backing, and the metal is often bonded to a plastic foundation.
   They are available in a variety of sizes and grits. Diamond sharpening stones can remove metal very quickly and can be used on the hardest metal. A diamond stone will even sharpen carbide tools quickly and easily.
   Diamond stones usually have holes in the surface to collect the metal shavings so that the sharpening surface remains clean and flat. They are used with water and are easy to clean up after use.
   Diamond stones are very useful for sharpening tools and for reshaping small parts. However they do not polish metal well and are very aggressive about removing metal, so they should not be used on critical gun parts.
   Stones are like a lot of other tools in that they accumulate over the years. But, to start with, you will need a good bench stone, preferably a double-sided one that has fine grit on one side and medium on the other. These are available from any hardware store.
   You will also need a selection of small Arkansas, ceramic and India stones in several grits and shapes. These are sometimes called stone files and are used in a lot of work on guns. Norton has an excellent stone file kit that includes both natural and man-made stones.
   Spyderco has a wide selection of ceramic stones, including bench stones in three grits. They also have ceramic stone files, including a kit that has four stones, including round, square, triangular and slip. They are housed in a leather pouch and are excellent for gun work.
   Store your stones where they cannot bang against each other or other tools. Keep them clean and never drop them on a concrete floor. I know from experience that
is usually a death sentence for the stone. But, with proper care and use, they will last a very long time. I am still using some small stones that I have had since the early ’70s.

Abrasive stones are ideal for honing and polishing engagement surfaces (1 top photo). Norton, one of the largest suppliers of gunsmithing stones, offers this set through MidwayUSA (2). Here, a stone polishes a trigger held in a universal sear stoning fixture, which maintains the correct angle (3). A Norton India slip stone sharpens a hand chisel (4). Spyderco also offers a bench stone and ceramic file set (5).