tank output psi and fps?

This may be a stupid question but if I throw an 1100 psi output tank on my mag and dial it in at 280 and then switch over to an 800 psi output tank will my velocity drop or will there just be less reactivity?

The velocity adjuster is a regulator, so it should be just less reactivity. However, you'll want to chrono and make sure of that.

i'm assuming that you are talking about a RT/ReTro/Emag/X-valve and reactiveness. as Dayspring said, the valve is a regulator and it should have no changes in velocity. but you should always rechrono the gun just to make sure.

There is some change in output pressure of a regulator depending on the input pressure change. It is usually a percentage of the input change and depends on the design of the regulator. A typical value could be 1%. So a regulator that is set to give 1100psi when the tank is full at 4500psi will only give 1070psi when the tank has 1500psi left. If the gun was a poppet valve running directly off the tank, it would only represent slightly less than a 3% change in valve pressure and therefore less than 9fps drop in velocity at 300fps. Now, the same 30psi change going into a second regulator such as a mag valve, would represent a 1% change as well. The change in chamber pressure would only be 0.3psi. There would be more inconsistency in the friction of the orings and paintballs than in a 0.3psi change due to air tank pressure in this situation.

So translating that over to a change from a 1100psi tank to a 800psi tank, a 300psi drop in input pressure would represent a 3 psi drop in chamber pressure which is about a 0.6% change in pressure for a level 10 valve system operating at 500psi.. It takes more pressure change at the high end of the velocity range than at the low range due to friction having a greater effect at the higher range. A 0.6% change at 300fps would translate into 1.8fps without friction, but it will be less than that due to frictional forces. Therefore, it would not be a concern because the velocity change when changing tanks would be less than 1.8fps.

I've been running two tanks, one at 1100psi and one at 875psi, and I've noticed a bit of a leaking problem in the level 10 by doing this. I set my carrier o-ring with the 875psi tank and when plugging in the 1100psi tank it leaks out the barrel. I'm assuming that the extra pressure going through the valve is just enough to mess up the seal that's made by the carrier o-ring. Am I right in assuming that it's the higher pressure tank causing this?

I'll try re-fitting my o-ring to the high pressure and see if it makes a difference. I'm just hoping it doesn't cause any bolt sticking issues when using the lower pressure tank.

It normally shouldn't make a difference, but the higher volume blast of air may move the carrier oring causing it to get pushed up past the vent hole.