Two changes were made. They changed the bolt, and changed the bedding block. I told them it was not as accurate as My regular Mountaineer and they made that change based on there findings as well. I am excited to shoot the new one i got. All the changes were made before any shipped out. Its a pretty exciting ML from top to bottom. All quality made American parts and lightweight. I hunted with Jeff the owner of Knight Rifles and Gordy this past weekend. They both hunted with the Ultralite and are really excited about the accuracy and the quality of this new ML.