Break-In

When I got my first TX 200 (1991) I was told that the more I shoot it, it will break in and get better. That gun had over 200,000 pellets through it best I can figure and it was better when I sold it (this I regret ) than when new. Just like a car engine (my business ) everything seats into its mating part and the whole becomes smoother.
 
Yep, all the above. Plus the barrel gets a little tighter from lead deposits, smoothing itself out like a river bed. Piston seals wear to perfectly match the cylinder. It all works to machine the system to near perfect tolerances.....for awhile .....then as time goes on from there the process slowly reverses itself.

It's like the circle of life. 😎

Kinda makes you wonder how long the perfection lasts, doesn't it? I'd guess that you probably get 1000 perfect shots between rebuilds.
 
Springers are mechanical things that have many moving parts. They have pistons, seals, springs, trigger assemblies (which have many parts of their own) that wear and mate with one another. As all these parts move and wear together over hundreds and thousands of firing cycles, they "mesh" and "mate" with one another and become smoother in their action. It's kinda like a new car. As the engine with all it's new internals gets a few miles on it and becomes "broken in", the fuel economy usually increases. It's because all the bearings, journals, piston rings ,etc have mated with one another and the engine becomes more efficient. A springer gets better with the miles as well. I don't know if this explanation helps, but I hope so. 
 
I'd say more like 10 - 20 K between rebuilds. (Or more) Heck I've shot 1000 pellets in one week.

Yeah 1000 shots in a week isn't hard to do at all. 

My point was that you probably get 1000 perfect shots between the "breaking-in" and the "wearing out". Since in theory the components of the gun are either in the breaking in, or the wearing out process....With a perfect spot somewhere in between.
 
You can speed up the process if you take the gun down and do some polishing in the proper places. The trigger is a good place to start. Also, if you are careful, swabbing the barrel with a mild bore compound helps get rid of some of the "high" spots. Then a good lube in all the right places puts you ahead of the break in game.

Do it wrong and it will cause more problems than its worth.