More about HandPumps and moisture in your Guns

This is GOOD news especially you being in Hawaii! Where if there is going to be moisture in anyone's gun from using a pump, it'd probably be yours. I am going to order the hill pump right now

 I had read somewhere that at 3300 PSI or whatever you're going runs that, the pressure is too high for there to be much water vapor in the air in the gun. That being said I swear I can see a poof of moisture coming out of my gun when I hand pump it in an area with high humidity. 

I've actually felt moisture coming out of my bleed valve before.

Have done some work with corrosion on steel and generally there is a threshold relative humidity where corrosion occurs. This is roughly 75-85% RH. I wouldn't think it likely putting that humid air in our rifles. If memory serves, condensation of water from the air is fairly independent of pressure but very dependent on temperature with low temps causing condensation. Just don't think we blow our PCP tanks down quick enough to lower the temperature to the point that free water will knock out in the reservoir. Out the muzzle yes but that is OK given it is cleared from the gun. Just my thoughts...

I pump my Marauder and that has been a concern. I will probably need to replace my Benjamin pump soon and will look into the Hill.

Here in humid Tennessee I am thinking the desiccant on the input side of the pump might well be a good investment.

Any other Tennesseans/SE US using it?

I'm using a Hill pump with the desicccant dryer in East TN. I've never seen any moisture when I open the bleed valve to remove the fill hose. However, I also only pump it in the house or garage where the air is less humid than out doors. Air-conditioning and/or dehumidifiers running in both places. My PCP's are primarily target shooting in the basement, or a quick pest riddance in the back yard. I have not had a reason to open the air tanks of the PCP's so take my use with a grain of salt. I figure it couldn't hurt to have it and gives a little more sense of security.

At a previous job using air compressors outside we had problems with air tools and moisture until we installed in line filter driers.

I'm in Jonesborough, TN and use Hill pump for a M-rod. When I installed a depinger, I didn't find any rust. But I'm thinking about using high pressure nitrogen because it is easier than pumping and completely dry. 

Be advised that the poof you see when you fire is likely the high pressure from the gun moving through the humid air outside the gun. I use air that comes from an industrial dryer and pump and still see the poof.

The poof is from the wave of low pressure that immediately follows the high pressure of the discharge.
Rapid lowering of pressure is adiabatic and will significantly lower the temperature of that air for a short ttime. That lower temperature makes the moisture in the environment (not the air that just came out of the barrel) condensate. Voila, a poof of cloud is visible for a short time.