Sporting clays is a refreshing change from the predictability of skeet and the limited variability that the game of trap offers (44 degrees side to side, 5 set positions, 8-12 foot throw height, 16 yd line, etc).
Lipomas are benign fatty growths that do not grow quickly, but of course they must grow from somewhere, so they do grow. If a lipoma is small, does not show without touching it, and is not painful, I recommend generally leaving it alone.
Lipomas are generally slow-growing. They are often removed if they become tender, or cosmetically bothersome to a patient. With a history of melanoma, I recommend following up regularly with a board-certified dermatologist. Any new growth, should be assessed carefully with your history.