This was initially part of another thread. As I started typing out a reply, I realized I'd jumped the rails and was highjacking the conversation. So here's a whole new thread.
Originally Posted by ChattanoogaPhil
a recurring theme when they speak about break in period. Use light velocity oils and "NEVER use any form of grease".
That makes perfect sense. I usually don't do anything special for break-in, I just take a new gun out and run it. That's what I DO, but here's what I THINK.
"Breaking in" is the initial period when all the rough (microscopically speaking) surfaces and tight fitting parts rub against each other and wear themselves down. It's the first wear that the mechanism is subjected to, and is greater at this time than any other point in the gun's lifespan. Break in is a good thing, as operation will become smoother with less frictional resistance.
By introducing all these fancy anti-friction lubricants, we are actually inhibiting the break in period. By using light oil as the manufacturer suggests, break-in might take a hundred rounds. With super-duper mega grease, break-in might require thousands of frustrating rounds and many trips to the range.
Can we accelerate break in by running the gun with NO lubrication? While that sounds like a good idea, it's probably not the best course of action. Similar metals when rubbed against each other under pressure exhibit "galling." That's when molecules from one surface come off and adhere to the other surface. It's as if the surfaces microscopically weld themselves together and then break apart. It's a bad thing, and must be avoided. Lubrication is intended to prevent galling. Don't run the gun unlubricated.
Another method of getting a perfectly running gun is to hand fit everything. This might involve locating rough or tight surfaces through he use of layout dye, then smoothing out those areas with files, scrapers, or lapping compound. It's common to see people doing this on their feed ramps, but to go beyond that without focused intent is probably not a good idea.
The best plan for a new gun is probably to just take it out to the range, and lubricate with oil as the manufacturer suggests.