41 Long Colt DA case, also known as the .410 Extra Long Colt, .41 L.D.A., .41 Long Colt, and .41 Colt Double Action. Suitable for use in most .41 Colt revolvers including the Colt Thunderer, New Army, New Navy, Army Special, Single Action Army, and the Bisley. Use #32 RCBS shellholder. Heel-type bullets and Hollow Base bullets that expand into the rifling are generally the best choice for projectiles. These can be found at Buffalo Arms or (208)263-6953.