...my Mossberg MVP LR in 5.56NATO. It has a 20-inch, 1/7 twist. I want to use 68-75gr bullets out to 400+ yards. I would like to use either IMR 3031 or IMR 4895, as they are readily available in my AO. While I have it, I don't think WIN 748 will give me the 2700+ fps velocities I hope for. TIA