Cool. That's an easy monument to find. It's very close to the Pennsylvania monument. If you come you should also take a side trip and visit the Monterey Pass battlefield in Blue Ridge Summit. It's about 15 minutes from Gettysburg. The 4th NY Cavalry fought in that battle.
Certain state permits qualify as "NICS Exempt" as the ATF has determined the permit requirements as an alternative to a NICS check. I believe that there is a box that is checked on the 4473 signifying a "NICS Exempt" permit holder...
I did it several years ago and will probably be going again now that my son has started school.
I have several friends who are very active in the artillery competition.
Send me a PM and I can get you some contact info.