John A. MacMillan III, age 49, died, unexpectedly, Wednesday, May 16, 2012 at Lahey Clinic in Burlington. He was the beloved husband of Christine L. (Mize) MacMillan. Born in Chelsea, November 10, 1962, he was the son of John A. and Sandra A. (Giovannangelo) MacMillan II. A Master Machinist who formally worked for Itek for 15 years, Mr. MacMillan worked on the Keck telescope for 9 years. The last 11 years he has worked for Axsun Technologies in Billerica. An active member of the Woburn Sportsmen's Association, John was the Chairman for the Smallbore while also serving in several different positions which he loved dearly. He very much enjoyed the comradery of his fellow sportsmen. John also enjoyed all shooting activities at the club and was an avid fisherman as well. Besides his wife and parents, he is survived by his daughters, Sarah and Rebecca MacMillan of Billerica, his brothers, Steven MacMillan and his wife Angela of Lowell and Patrick and Wayne MacMillan, both of Billerica, his mother-in-law, Catherine Murphy Mize of Billerica, and his niece, Sara MacMillan of Lowell.