Best, or at least good, materials for internal polishing?

[Hasaf]

Quite a few years ago, about 20, I had a Makarov that had an unpleasant trigger. I did a detail strip and polished all of the mating parts (other than the sear) with green scotchbritre pads and a mild polishing compound. I had not trouble getting all of those parts to a good shine and it had a very positive impact on the pistols performance.

The reason that I used green pads is that I had them as my job, at the time had me frequently using them to clean and polish mechanical parts (high-volume copier repair).

I am getting ready to do a detail strip on a CZ Scorpion EVO 3 trigger pack. The purpose is to polish it. If I remain unhappy with the trigger pull (it is currently over 10 pounds) than I will put in a spring kit; but I like to do things one step at a time.

Is there any good reason to not use scotchbrite pads and flitz polishing compound, as I did in the past?
If so, is there something that should be used instead?

 

[jaguarxk120]

I like to use Mothers Mag Wheel polish on a heavy cardboard stock.
It is a flat surface and there is less of a chance of rounding corners.
The Flitz and Mothers abrasives cut slowly and leave a surface like chrome.

 

[beag_nut]

If one wants a safe gun after modifications like this, the correct methods are to do what gunsmiths do: use hard stones, not anything soft like pads or papers. The soft materials practically guarantee rounded edges, which greatly increase unwanted discharges. A dear past-away friend, who earned money also as a well-respected gunsmith (of decades ago) had the harshest criticisms for people who used anything but hard black or white Arkansas stones. For a step-by-step demo of a really good smith, see this youtube:

 

[jaguarxk120]

Stones are great for some use's but sometimes too much metal can be removed.
card stock with a hard backer will provide a flat surface and the cardboard will carry/hold
the polishing medium.

 

[beag_nut]

Stones are great for some use's but sometimes too much metal can be removed.

.

Not true, if the hard Arkansas stones are used. Quite the opposite, since their "grit" sizes are so fine that it often seems like very little is being done. Which is exactly the point.

 

[Kp321]

Internal polishing can be taken to an extreme. If it doesn't touch anything else, it doesn't need to be polished. I use x-fine Cratex and hard Arkansas stones.

 

[straightshooterjake]

I will offer another vote that hard stones should be used whenever possible. When smoothing an action, the goal of polishing is to produce flat smooth surfaces. You want to take the high points off so that one flat surface will move smoothly against another. When you use soft polishing mediums, then wavy surfaces become shiny and wavy. They do not become flat.

I do nearly all of my polishing work by hand with stones. I have a variety of stones for different purposes, but for fine work, I generally recommend Brownell's white ceramic stones. I only use power tools and and soft media for internal surfaces that cannot be reached any other way.

Note that when I talk about polishing, I am primarily talking about smoothing double action triggers, such as on revolvers or the first shot from the Makarov. Most of the tolerances for double action triggers are not too fine, and double action triggers are a reasonable project for the careful "kitchen table" gunsmith.

The hammer and sear engagement surfaces for single action triggers are a different story. A good single action trigger requires very precise surfaces in order to be safe and have a good feel. I believe that sear engagement surfaces should only be touched with hard stones and proper jigs. And even with the proper jigs, some experience and practice is required to get good results. I highly recommend looking for a skilled gunsmith if the hammer and sear engagement surfaces need adjustment.

 

[entropy]

Ceramic stones work best for trigger work. Use them sparingly, check fit and finish often.I had an infinite supply of trigger parts to learn with, courtesy of Uncle Sam. You don't, so be careful.

 

[Hasaf]

Well, that experiment is done.

First, I am glad I did it if for no other reason than to see how to detail strip the trigger group. I focused on metal to metal parts with very little touching of the hammer sear contact points. There I just used some polishing compound and Popsicle sticks. There is no way I want to risk anything that may remove metal from those surfaces; just polish them.

Several other parts got various treatments from green pads to stones.The intent just being to make all the parts that touch other parts smooth, no reengineering, just smoothing.

The end result was subjectively smoother. Yes, there are tools to objectively measure trigger smoothness, I don't have those tools. As an objective measure, the trigger seems to have lost about two pounds. I say about because my trigger scale only goes to eight pounds. Before the work it was significantly past the scale and I estimated between 11 and 12 pounds. It is still outside of the scale; but I estimate it to be about 9 pounds.

I will continue the work when my HB spring pack arrives. I like to do things like this one step at a time so I can see the effect of each change.

 

[4v50 Gary]

Use soft and then hard arkansas stones.

 

[dfariswheel]

Note that when we talk about "polishing" we DON'T mean "like a mirror".

What we mean is to SMOOTH critical areas that have machine marks or burrs that cause friction or rough operation.

Polishing parts to a mirror shine or simply polishing to make them look nice does absolutely nothing for smooth operation.
In fact, polishing to a bright or mirror shine often ruins the parts by removing metal from critical surfaces, or by breaking through the surface case hardening that prevents wear of the parts.

Real gunsmiths use fine stones and in SOME cases a flex shaft and rubber bonded abrasive tips.
We don't use soft polishing pads or fill an action with grinding compound or toothpaste. That will attack surfaces that should not be touched and you can't control what gets abraded.
Unless there's a specific reason for doing any work on a surface we don't touch it. Less is more.