I mentioned the use of abrasives in my post up-thread and decided I have to introduce some hard earned wisdom. Caveat: First, I have rarely used abrasives on my rifles, I have used abrasives (JB Blue Label) on one of my 1911s that had really bad copper fouling from lack of regular cleaning and that was just once.
The bottom line here is that if you are going to use abrasives you really have to know how to use them, and more specifically, how abrasive is the compound you are using. This will determine the limits to their use. So, I will tell you what I know about them here.
I've gained this knowledge over three decades of detailing my vehicles. This includes the use of buffers and abrasive polishes on paint clear coat. I have leased all of our vehicles since forever so I do this on 2 new vehicles every three years. That's a lot of cars.
Like rifle barrels, all clear coats are not the same. From experience I know that Japanese vehicles have the softest clear coats, while German ones have the hardest. This then calls for different polishing compounds for different vehicles. I use Menzerna products (German).
I'll cut to the chase. I tested two shooter favorite barrel abrasive compounds against the clear coat polishers that I'm very familiar with. I was quite surprised. My test is simple because I am extremely familiar with abrasive polishers. Below is a picture of the ones tested and the abrasiveness scale is pictured from left to right, with left being the mildest. I will post more info below the picture.
Caveat! If you are going to try this yourself make sure that the product is well mixed and that there are no abrasive clumps in suspension.
The way I test is simple. The finger test. I put a small amount of polisher on my finger and slowly apply it to a blank index card with light pressure. From experience I can feel the amount of abrasives and even the size. I know the Menzerna products well and have used them many times, The one on the left is for Japanese cars (softest clear coat), the one furthermost right is for German cars (hardest clear coat). One really good thing about these polishers is that they are designed in such a way that the abrasives dissolve during use! SO, its very hard to screw up because after less than a minute the abrasives are dissolved to almost nothing. In my tests J-B Blue label dissolves too but still leaves particles behind, and Iosso seems not to dissolve, at least not as fast as any of the others.
I was however quite surprised that J-B abrasives are the mildest of all the ones shown, and Iosso, which I thought should be the mildest is up there with the more abrasive ones.....
Abrasives are made to REMOVE minute parts of the surface they are applied to, period. How much you can remove without damage, be it clear coat or steel is the key. Properly used, how much they remove will depend on the hardness of the surface. 416R stainless is the most common one used on rifle barrels, and it is not the hardest stainless by a long shot. It has a HRC (Rockwell scale) of 26~31. Some regular barrel steels are even softer. In comparison, I own expensive Japanese knives that have HRCs into the 40s. Car clear coats are quite hard, but use a different hardness scale that does not convert to HRC. And polishing clear coats polish them to glass smoothness. But at that point they are fully exposed and need to be protected (enter waxes and such). Same with barrels. They are left in the raw...
So, if you don't know how to use an abrasive, don't. If you still want to use them, do it sparingly and seldom. It is much better to use regular barrel cleaners, and often, than abrasives. And abrasives every time you clean - big no no. That's like using abrasives every time you wash your car. Pretty soon you have no clear coat!
And that is what I do. If I ever shot so much that barrel wear and replacement became a frequent issue, then I would consider abrasives but would only use them every 2-400 rounds, sparingly,
