Well, as we discussed in prior threads, Louisiana Shooters Unlimited is purchasing a S&W M&P 15 Sport and a Colt 6920 for students to use during our carbine courses. We will take photos, record round counts, keep track of ammo types, document issues, and keep the rifles close together in terms of rounds down range. Every 1500 rounds or so, we will shoot the rifles for groups. Any thing else that we should measure or track over the life of the rifles to give an accurate review of the two rifles as we track their use in identical harsh training environments? Thoughts?