Check out Indiana Multigun's website and Facebook page (if you do that sort of thing) for some info, rules, and scheduling, and just show up. Somebody on here recommended talking to Deb at Plainfield Shooting Supply to me, that'd be somewhat close for you. I'm just getting started as well, and have gotten a lot of good info here as well from some of the guys at the range here in the Fort Wayne area that hosts some of the matches.
Almost everyone I've talked to has said to bring whatever you have and shoot a match before buying a bunch of equipment, so I'd say your rifle setup would be fine. Most of the guys I've talked to are using semi-auto shotguns, but there are pump-actions used as well (I'm going to use my 870 this year till I decide if I'm going to stick with it). If you're in the market anyway, Mossberg makes a 930 semi-auto that is tricked out for 3-gun that might be worth a look. Lots of the hard-core guys shoot a Benelli M2 or Remington Versamax.
There is a ton of good info out there for just general 3-gun info that will help you figure out where to spend your money. Good luck, and I hope to see ya at a match this year!
Thanks, I sent a request on the Indiana Multigun website for info and liked their page. I have read a little up on the rules and divisions. That was the exact shotgun I was looking at, the Mossberg 930 SP Blackwater. I am definitely going to do it, I am super excited.
PM me and I can try to help. I got my son get started last year and learned a lot in the process.
In short, reliability and speed costs money. Once you start and have fun, you will be spending more money on items to make it more fun. There are a lot of great guys that will let you try a shotgun or rifle once they get to know you to see if you like the item and so you can shoot if something breaks. In general, a great bunch of people.
Basic entry will be:
Shotgun: any 12ga; 3 choate shot shell carriers; Magazine feed will put you in open class.
Pistol: Any modern doublestack pistol. Most use 9mm that are striker fire so they don't have to use a safety (Glock, MP, XD). Have 3 mags and a mag holder and holster with good retention. Look at the XDM of what a very basic start would be. Upgrading the holster will be one of the first things you do.
Rifle: Any iron sight semi-auto in a military caliber. Basic AR or AK works great. If you have good eyesight, at most add a Vortex Strikefire Red Dot and have 3 mags. If you have more money add an 1x4 optic. Anything beyond that or if you run an optic and another sighting system, that will put you in open where anything goes.
Other items: gun belt, bag to carry long guns, ammo can to carry ammo, and safety equipment. You may want to upgrade to a running stroller off crags list and walmart atv gun mounts to move all of the equipment to the different stages.
But bring what you have, a way to carry ammo, and ammo then the ones there can help. It also helps to go watch a match once just to get a feel for what is going on.
Fishnhunt is talking about the JM 930(I think). The blackwater is more of a defense style, I think it has rifle/slug sights and I'm not sure if it has chokes or is cylinder bore.
Your 870 will work fine, look into a nordic extension to get capacity up to 10 or 12. Have some chokes and know your patterns and distances that they are effective.
The 3-9 will work but it'll be slow and you'll be shooting most of the match with your gun turned 45 degrees. Most targets will be between contact distance and 50-100 yards. You might have 4-8 targets per match out at 2-300 yards. You can use your current set up and not be in open. A red dot and Magnified optic will put you into open.
If your going out to buy a pump shotgun take a good look at the Benelli nova or super nova. Most popular pumps in 3 gun. If you can afford $500 or so the new Stoeger M3000 is getting some rave reviews over its cousin Benells like inertia system. These look be the hot ticket for an entry level semi auto 3 gun shotgun.
I'm with Rabbitdave on this one. His advice is right on, just show up with what you have and if you are a gun short there will be plenty. This will give you a great idea on what equipment people are using, and then you can see what works best for you. The sky is the limit in 3G, keep it simple in the beginning and focus on SAFETY, ACCURACY, and get your HITS. Speed will come later after you have got a few runs under your belt. There are a lot of people that are more than willing to help you, just ask and let them know you are new to the sport. See ya in Atlanta.