Unfortunately, it is not legal to hunt turkeys with airguns in Montana. High powered PCP airguns are relatively undiscovered in Montana, as you never see them at the retail gun dealers. They sell "toy" airguns mostly that will not impact their firearm sales. Quality pellets like H&N or JSB are unavailable here and strictly a mail order proposition. Our airgun laws are very antiquated. Also, with all the excellent deer, antelope and elk hunting we have here, that is where the major hunting interest goes. However, the Bull Mountain area where I live has the highest turkey population in Montana. They roam around peoples yards like chickens in some places. Even in town, I once saw an old woman that was sweeping snow from here sidewalk and shooing away several "wild" turkeys with her broom. Last winter, three turkeys nested at night in the trees across a vacant lot behind my house. Very few people around here hunt turkeys, and since moving here in 2007, there seem to be more turkeys around every year.
Personally, I much prefer sharptail grouse to turkeys, much better tasting and I have killed a few of those, as they are part of my sportsman license every year that I buy that includes fishing and hunting. It even includes elk and grouse, but no turkey or antelope. Rabbits are considered a pest in Montana and you can hunt them all year long with no limit and no license. Go figure.