Would an astigmatism have a profound affect on my marksmanship?

I've had an astigmatism since I was young, and just recently decided to start actually shooting after having been a gun collector for quite some time. My vision is about 20/40 or so. Is there a distinct difference between shooting with corrective lenses that correct my vision to 20/20 and shooting with actual 20/20 vision? I've also considered potentially joining the army after college, would my vision have any effect on what jobs (that have a heavy emphasis on marksmanship) I would be permitted to do. If so, would corrective surgery open any restricted options?