Happy to help.

I was thinking last night about whether there are any similarities between a bullet travelling throught the bore of a gun, and a piston travelling through the bore of a cylinder.

The first thing that came to mind was piston speed. 150 fps was your number for a bullet. Compared to a piston, which has a mean piston speed, that is very high. Maybe I am stating the obvious. For medium duty diesels, we used to consider piston speed as an indicator of engine durability, due to their long strokes and high maximum piston speed. Out of interest, I worked mean piston speed out for your 4.6. With an 85 mm stroke, to achieve 150 fps, you would need an engine speed of 16,200 rpm. Said another way, at 2000 rpm, you would have a mean piston speed of 18.6 fps. That is almost an order of magnitude less than the gun example. My conclusion is that if the product works on a gun, and it anecdotally does, that doesn't necessarily carry over to it working in an engine, just based on the speed alone.

Next up was whether it would stay in there, and continue to protect the metal. In a gun, it is wiped on, and then a round is fired. OK, maybe lots of rounds. I equated the bullet in the gun barrel to a piston in a cylinder bore again. However, at 2000 rpm, the engine piston goes through the bore 240,000 times per hour (2000 x 60 x 2, as it travels up and down). So, if you drove for four hours, that would be the same as firing almost a million rounds. My question to myself is, if you wipe down a gun bore with this product, and put an imaginary one million rounds through it, would we expect the residue from the wiping oil to still be lubricating the bore? That is because the product is advertised as a one-time application, it apparently doesn't need to be continually reapplied. My conclusion, just using reason, is that after one million rounds the original lubricant is not likely to still be there.

I don't know how the manufacturer made the leap from having developed a gun oil, and concluding that it would be a good oil additive in a modern engine, but it doesn't appear to hold up to scrutiny.

Comments and corrections welcome.

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