I'll add that your idea that filling to the bottle first will prevent condensation from making it into your guns is correct. Ideally you want to prevent condensation from occurring in the bottle too, but your idea is correct - the fact that the fill charge cools down in the bottle, and then cools more as the pressure drops when it flows to the gun's reservoir at a lower pressure insures this.Not to discourage you, but do know that filling to a bottle and then filling your guns will be "harder" on the Yong Heng, and most likely cause it to wear out or fail sooner than it would if you were using the same amount of compressed air by filling directly to your guns rather than the tank first. This happens for a few reasons: - You will be running the compressor to higher pressure levels almost all of the time, and this is harder work for it. To explain, assume you fill a gun to 3000 psi: - When filling the gun, you run the compressor from a lower pressure (say 2000) up to 3000 and stop. - When filling the tank, you will refill it when it gets down near 3000, so the compressor will run from there up to 4500 or so - You will be running the compressor for longer intervals of time as the tank is bigger, and doing so at these higher pressuresSo that is a factor to consider - you may need to replace it or perform maintenance sooner when filling tanks instead of guns. That said, it is what I would want to do, and actually do with a Shoebox compressor, but those are ideal for filling tanks instead of guns . . .
https://www.airgunsofarizona.com/Tanks/FillCalc.html