As air pressure increases, it's ability to hold moisture is reduced. Think of squeezing a wet sponge. This excess moisture will condense and yes, you can turn a cyl upside down and blow the liquid out. But obviously the best option is to not get too much moisture in, in the first place. That's not to say that even the amount of moisture that a compressed air cly can hold
Here's my take on all this. First, use good procedures, keep the air fill line and any filters below the gun level while filling. Make sure there is a cotton filter in the air line to keep moisture from blowing up and into the gun. That will go a long way to keeping moisture out of your rifle. A desicant filter is fine and will likely add some minimal drying, especially on the high pressure side.
IMPORTANT: every do often, open you gun up and take a look. Open the cyl and check for moisture. This will tell you FOR SURE if you're doing a competent job of eliminating moisture in you system.
Open you fill line every few months or so and see what it looks like, many have steel fitting and will rust letting you know you have moisture in the lines, but not necessarily in your guns. This is just an indicator because if you pump air, you'll have some rusting of steel fittings.
I used to pump air and never had a filter and never any moisture in my guns, but lots of rust in my airline fittings, soooo, I decided to feed my compressor nitrogen and all problems solved.
