Keep your ear pro handy. I have never fired an AR in a truck but Travis has mentioned the brass gets flung into the heater vents. Personally I would want some type of light closed breach manually cycled weapon like a bolt gun with a 20 inch barrel on it.
Maybe a Tikka T3 lite in 308 or 260, I have never been crazy about the 243 but I guess with 100 grain bullets.
http://www.aihpa.com/Sponsor/Tikka_T3_Mag_Options/Tikka_T3_Mag_Options.htm
