I used to shoot with that group when they were the "Tactical Arts Group" at Nashua F&G. Great bunch, fun times and good training! Of all the things i miss about living in NH, that's at the top of my list :-(
In regards to the carbine, you don't need a gizmoed out M-4gery with $500- worth of optics to shoot. Take whatevery you have-a lever gun, M-1 carbine, Garand, Enfield or Mauser (learn to use stripper clips first!), SKS, whatever. If your goal is to be competitive, then you may want a space rifle. if your goal is to improve as a marksman and have a good time, run what you have! I never found them to be the types to look down on the shooter with the "average" rifle.