Sweet Spotting Your Regulator
(Note: Do not sweet spot your regulator if your marker is pressure sensitive and has to have a very specific PSI input to operate like spool valve operated markers. Most markers however have a broad operating PSI range and sweet spotting your regulator will help a bunch.)
Sweet spotting your regulator is one of the most productive things you can do in trying to make your marker more effecient. The more efficient your marker is, the more shots you get from a tank of gas. In sweet spotting your regulator you find out what your optimum PSI input for your marker is. Sweet spotting the regulator is not a quick process, but it is easy at least. It is time consuming, and requires a good deal of air, and some paint. You also need a chronograph (those handheld radar chronographs are great for this) If your poor like me or don't have access to a chronograph you can eyeball it. If your fps is increasing you will shoot farther. If you fps is decreasing you will notice your distance is decreasing.
Start by turning your inline regulator all the way down to zero psi, also set your velocity adjuster at two turns in from all the way out. Now, increase your pressure slowly while shooting the marker over the chronograph. Adjust your pressure 25 psi at a time, and take five shots (give or take) over the chronograph to establish a velocity at that pressure. Continue this process until the velocity or distance peaks, which is when any increase in pressure will result in a decrease of velocity. This point varies for every marker and is the most efficient pressure setting for your spring set. When the velocity drops, start lowering the pressure (5 psi at a time). The velocity should start to go up again. Gently nudge the pressure lower and lower (using those small increments) until any change, be it up or down, results in a lower velocity.
Now that the regulator is sweet spotted, you need to adjust the velocity adjuster to reach your desired velocity. With any luck, the regulator will sweet spot right around 290 fps.
Another excellent way to increase your effiecency and also your accuracy at the same time is to get a good barrel and a nice paint-to-barrel match. Read more about this in the Accuracy 101 article.