Reply To: Vulcan .22 Speed low first 3 to 4 shots
It seems that your regulator’s brass screw may be backed out a bit too much. Try decreasing working pressure to a little below 125 BAR. It could be that the shaft inside the reg housing doesn’t fully seat itself quickly enough (to prevent unregulated air from entering the regulated air chamber) until after the 10-15 minutes you indicated. This is one of the main reasons that cause this kind of problem.
If the advice above doesn’t eliminate the problem, inspect the regulator for worn internal and external O-rings. You may also want to try cleaning and relubing the entire regulator assembly before reinstalling it. When you lube the O-rings, piston, and Belville washers, make sure that you do so only lightly. If the cause of your issue is not coming from a blown O-ring, it may just be that one of them (or more than one) is being extruded.
In my opinion, you do not need a new regulator. Most often, it’s just a matter of cleaning and servicing the factory regulator to get it to perform the way it should. Bear in mind that even the best of air rifles leave the factory not optimized to perform at its best. In extreme cases, with respect to the issue at hand–though not even an intensive labor on the part of the self-tuner–it could be just a matter of resurfacing the delrin seat/seal/face that the reg piston shaft pushes itself against.