Hello All.....Well...We DO blast the rails when we do a Tuff-Gun re-finish job on a semi pistol! Now, having made that statement, there are several items that must be mentioned.
We do not use silica sand for our abrasive blasting media. It's too rough and will eat metal if the pressure is high enough or allowed to blast on one spot. Glass beads don't work well either since they tend to polish the metal. We use a product called Black Beauty which does an excellent job of old finish removal and surface preparation but without being too aggressive. It's a little more expensive but worth it.
Alloy frames are just given the "quicky" treatment to remove the gloss but not damage the Anodizing. All alloy parts are given a Mil-Spec chemical bath to harden any areas that had the Anodizing worn thin and to prepare the surface for the new finish.
Steel is blasted right down to bare metal and Parkerized, including the slide rails.
We use only Gunkote that's molly based (Mollybdenum Disulfide) because it burnishes with use to a fit that is slicker than original. A note on so called "Molly finishes". Many of them have no Mollybdenum Disulfide at all!
Certain areas, like slide rails, get the Gunkote applied heavier than others. How thick depends on how loose it was to start with and the base metal. All steel = heavier..Alloy = thinner, etc.
Then the slide rails are hand lapped but no lapping compound is used! It's a polishing compound that will not embed into the metal and gives a very smooth final finish.
Ok, now that we're to the subject of hand lapping (Finally!) there are some special considerations that must be taken into account. Slide rails are machined into the surface of the metal. Most manufacturers make a compromose between speed and quality. That means that operating clearances may be a "bit on the loose side".
If you were to look at a brand new slide rail under a microscope, you would see that the surface is not smooth or flat. It has bumps, lines and dips. It is NOT smooth like a piece of glass. Many times, you can see this without a microscope!
The idea is to apply more molly-resin Gunkote than needed and then hand lap off most of the excess. The final fit is acheived by actual firing to burnish the rails to match each other. Yes, sometimes the finish may be polished thin in some spots but those are the high spots that were always carrying the load. The difference is that now, the low spots are doing some work too. The result is a reduced friction coefficient that you can feel.
Yes, there are shooters who may disagree with me on this. But please consider this: It's a metal on metal contact that takes a lot of pounding. It's a bearing surface but it is NOT a bearing. There will always be wear marks on the finish. The idea is to get as much of that bearing surface as possible to take the load.
Keep Yer Powder Dry, Mac
Mac's Shootin' Irons
Tuff-Gun Finishes. The Name Says It All.
