Respiratory protection should be the last measure to take after engineering controls are considered an implemented. If you suspect hazardous Pb levels, you should discuss it with the range owner. The problems with respirators are: they require a fit test to ensure proper size and fit; the filters have a limited lifetime and require periodic replacement, they are uncomfortable and can cause safety problems in and of themselves; they cause an additional respiratory load that may present a hazard to those that have pulmonary or cardiac risk factors.
I understand your concern for your health, but you should investigate other options first. If you decide that you need a respirator, get a quality half face (MSA, Draeger, 3M, etc). Filtering facepieces ("surgeon's mask") are not what you want.
You can always have your physican prescribe a blood lead level test to see if it is real issue for you right now.