Go to split screen mode and choose Free-For-All. Have one player select the Marksman combo (includes the R700 rifle and M9 pistol) while another player selects the War Fighter combo (includes the G36C rifle and the G3 rifle). Have the player with the War Fighter combo kill the Marksmanm. Then, take out the G3 and trade it for the R700. If the person has shot a few rounds, it will be refilled to the maximum. The R700 holds 32 bullets per round. If you shoot one clip, go back to the body to refill again.