Hi, Andrew,
If he was killed on July 1, it was likely in the railroad cut north of Gettysburg. The 42nd Mississippi and the rest of Davis' Brigade was trapped in the railroad cut and mowed down by Union soldiers.
If you haven't seen it, there's a great YouTube on Davis' Brigade on the first day at Gettysburg, available here.
It's unlikely that anyone from the regiment was killed on July 2, since the regiment saw no action on that date. He may have died on July 2 of wounds suffered on July 1, or he may have died on July 3, when the remnants of the 42nd Mississippi and the rest of Davis' Brigade were on the extreme left flank of Pickett's Charge.
I'm also a descendant of a veteran of the 42nd Mississippi,.Cpl. William Jefferson Killingsworth of Company G. He survived the brutal fight at the railroad cut on July 1 but was captured during Pickett's Charge on July 3, He died in February 1864 while a POW at Fort Delaware and is buried in a mass grave there.