Gun Kote: A Precision Coating

"m I not telling you anything you don’t already know when I say that maintaining close tolerances is of paramount importance when building a custom handgun. To the custom gunmaker, being off by .01 inch is unacceptable, and the master practitioners of this trade dedicate themselves to holding critical dimensions to the thousandths. For example, the industry standard for slide-to-frame fit is plus or minus .003 inch.

The masters’ requirement is plus or minus .001 inch, and while a match barrel on a .45 would have a plus .003 tolerance at the bushing, it would be .001 inch at the rear of the hood. This can present some concerns, particularly in cases where the gun being worked up is in the white (wearing no finish whatsoever) or has had its finish removed for the duration of the build.

When sent out for plating, coating, or bluing, the piece can come back with a finish so thick some of the previously taken The upper is finished in gunmetal blue, while the frame is a custom-blended metallic gold. To say it is gorgeous in color would be an understatement. steps toward precision have to be taken again. Though I don’t vainly count myself as equal to these best gun builders, I faced the aforementioned problem recently when a Springfield Armory M1911A1 was returned to me after a plating job.

The slide-to-frame fit was all out of whack and entirely too tight to assure mechanical repeatability. As a result, the fitting had to be done over, and the plating company was promptly removed from my list of suppliers. If I’d known then what I know now, I wouldn’t have lost money on the job. Now I know about TR Ten-Ring Precision A high-tech abrasi d nt polymer coating, it was first developed for military weapons and used initially by Navy Seal teams. One reason?

It can withstand a 500hour salt-spray test and still meet machine-gun firing requirements. More reasons? It has proven to be resistant to chemicals, oils, and solvents used in the automotive, aviation, and machine-tool industries and withstands temperatures up to 500 degrees Fand down to minus 250 degrees. Finally, Gun Kote loses little to none of its capability even when applied in a coating as thin as .0004 inch, which is ideal for close tolerance work.

What I like most about the product is that it’s a precision coating I can apply myself. The gun I’m working on never leaves my sight. What You’ll Need Most well-equipped shops will have the necessary items for using Gun Kote on hand. If you don’t, you can build or purchase most of what is required at reasonable cost from local sources.

The list includes an airbrush or touch-up spray gun, a sandblast cabinet, #2 or finer blasting sand or 100-grit aluminum oxide, latex gloves, a fume filtering mask, a well-ventilated working area, and a homemade oven with thermostatic control (details to come). Since the solvents that you may be using are flammable, work with a cautious awareness of that fact. Applying the Finish Disassemble the firearm completely including all pins and screws. Plug the bore and breech with a cleaning

patch. Do the same with any openings you don’t want to finish such as the chambers of a revolver cylinder. Shake the can of Gun Kote for two minutes before pouring any into the reservoir of your sprayer. Any spills can be cleaned up with alcohol. Slip on the gloves, and degrease every part of the gun with TR Cleaner/Degreaser. Don’t handle the degreased parts without gloves on; the finish is only guaranteed if TR Cleaner/Degreaser is used prior to proper blasting.

The latter follows immediately to remove all scale, rust, previous finish residue and other surface deposits. Blow the parts off with clean air. Don’t chemically degrease the parts again. At this point it’s a good idea to use another product from Ten-Ring, K- PHOS, to spray on the metal at room temperature. This gives you a phosphate finish, which is a first-class primer for Gun Kote that makes the final finish even tougher. Place the degreased, blasted, and phosphated parts in the oven.

Hang and place them so they don’t touch one another. Wires attached to smalldiameter welding rods inserted through the side walls of the oven work well for this purpose. Heat the parts to about 120 degrees (or 100 degrees if applying the stainless-steel finish). Still wearing gloves, remove apart from the oven by its wire and spray Gun Kote over it using fast, light passes to cover the entire surface. When the spray touches the warm metal, any solvent it contains should evaporate immediately.

For parts subject to heavy wear, a second coat can be applied after placing the part back in the oven for 20 to 30 seconds and spraying it again. A coating of .001 inch on outside surfaces is fine, but on close inner tolerances, .0004 to .0005 is best. Note: When applying the stainless-steel Gun Kote, hold the applicator about 4 inches from the work to prevent the coating from drying before it reaches the metal.

Immediately after coating the parts, run alcohol or acetone through your sprayer to clean the nozzle and prevent it from being useless next time you need it. Use alcohol to clean your skin, followed by a good-quality hand lotion if you want to keep your fingers free of cracks that invite infection. Bake the coated parts at 300 to 325 degrees for one hour. The stainlesssteel finish is cured at a constant 300 degrees for the same length of time. Aluminum and magnesium parts are baked at 275 degrees for 90 minutes.

After removing all the cured parts from the oven, reassemble the gun. If the coating you have applied is too thick in tight-fitting places, buff it lightly with 0000 steel wool, but be careful not to buff the corners to the point where bare metal shows. By the way, sharp corners provide no surface to stick to and should be beveled or rounded for best adhesion. This work is completed prior to blasting, of course.

Building a Homemade Oven The housing for a very efficient oven could be a cheap gun safe or a standup locker approximately 4 to 6 feet Cookie can with Top and Bottom Cut Out (Optional) Universal Thermostat Bricks tall by about 18 inches square. It should be insulated with at least 1-inch-thick air-conditioning duct board with the foil side facing inward. A large electric range-top coil fastened to the bottom of the oven or raised on fire bricks makes a perfect heat source.

A universal 120/220 thermostat controls the temperature and a 1/4-inch-diameter hole in the center of the front door accommodates the installation of a Brownells bluing thermometer so you can read the interior temperature and regulate the thermostat accordingly. Have a look at the accompanying drawing that approximates your end result. What it doesn’t show are the transverse insertion of 1/4-inch gas Gun Shop Oven Dayton 1/100 Horsepower Motor W. W.

Grainger Fan and Extension Shaft (You make the extension shaft.) Bluing Thermometer 220-Volt 10" or 12" Electric Range Coil

welding rods from which part-supporting wires are hung, or the use of high-heat tape to seal up any interior seams in the insulation, or the oven door seals which, if installed around the door, will make the oven more efficient. Troubleshooting Gun Kote Finishes If it turns green, the part has been left in the oven too long or the temperature got too high. If the coating beads up or comes out rough on the metal when first applied, the metal is too hot.

When a solvent such as acetone takes off the finish, the coating isn’t properly cured and should be returned to the oven for at least 45 minutes. There is no known solvent for cured Gun Kote. Its removal can only be accomplished by blasting. Use nothing coarser than 120-grit aluminum oxide; heavier grits could change part dimensions. When the finish chips or peels, the surface has been incorrectly prepared, oil has leached out of the surface, or you made the mistake of blasting with glass beads.

If the coating beads up on the surface or sprays out in strings, the mix is too thick. Add MEK solvent to thin it out. If the finish cracks when two parts are screwed together, such as a compensator and slide, you applied excessive coating at their interface point(s). If the stainless-steel finish turns out rough, the metal was too hot or you held the sprayer too far from the surface. You could also have too much air and not enough coating passing through the sprayer.

Increase the flow of Gun Kote and/or decrease the air flow. Finally, if you get "fish eyes" or bubbles in the coating, there’s oil or another contaminant either on the surface or present in the sprayer’s air supply. About MEK and Gun Kote You will seldom if ever have to use MEK (methyl ethyl ketone) to thin out Gun Kote unless the coating has been standing idle on a shelf for a year or so and the solvent has evaporated from the container. MEK can be found at any ACE Hardware or Home Depot store.

Now I’d like to make a request. Take another look at the photo of the Colt pistol on page 7. It was built by one of those master gunsmiths mentioned earlier. Has it been plated or blued? The answer, of course, is: Neither; it’s wearing Gun Kote. As you can see, it’s a two-tone finish. The slide wears Gun Kote in gunmetal blue, which looks like the old Smith & Wesson carbona blue. I saw this extended-slide Colt close up at the SHOT Show earlier this year.

No picture could do it justice, and I was even invited to handle it and check out the action job. Magnificent. The well-todo gentleman, I presume, who paid for the build chose the colors from Gun Kote’s broad spectrum, which includes flat black, semigloss black, flat and semigloss OD green, flat or semigloss light or dark gray, flat white, stainless steel, brown, tan, gold, red, international orange, royal blue, and clear. This by no means completes the list of possibilities.

By mixing primary colors, virtually anything is possible. How about a purple SIG or a pink Lady Smith? A Few Final Thoughts When I cycled that pistol at the SHOT Show, it wasn’t just smooth; it was silky smooth. Much of that was due to the skill of the builder, but he told me about another contributing factor, Kellube M12, a 100-percent synthetic gun lubricant. Unlike petroleum oils, it doesn’t encourage carbon buildup, thereby lengthening time between cleanings.

It coats metal with a protective film that eliminates oxidation and corrosion. It doesn’t thicken up at low temperatures or thin out at high ones, or so the builder said as he handed me a one-ounce bottle of M12. The bottle flew back home with me and I’ve been using it ever since. You know what? The gun builder was right. Let me leave you with a little advice about air brushes. For a number of years, I’ve owned a Paasche model designed for use by professional artists.

It’s been indispensable for touching up stock finishes or laying down original wet-on-wet camouflage patterns. Its spray width is very controllable, but it’s too small for quickly applying Gun Kote to a pistol or revolver frame, let alone a barreled rifle action. So I looked around and found exactly what I was looking for in the Eastwood A & Supplies catalog Their #11612 Grav Style Airbrush is adjustable from a fine line to a 2-inch-wide fan pattern.

The same company offers oil-less compressors and a little item called a filter regulator that controls the pressure to the airbrush and cleans the air before it reaches the sprayer’s feed line. If you don’t already have an airbrush and a source of clean, dry air, these products are highly recommended. I