Winchester Xpert Thumbhole Target Gray SRWinchester Xpert Thumbhole Target Gray SR Overview Featuring a great looking laminated stock with adjustable comb, Winchester Repeating Arms looks to dominate the rimfire bolt action market with the Xpert Thumbhole Target SR. When designing the Xpert, we put our sights on accuracy and added features to help you get the most from the rifle. Foremost is the Rimfire M. O. A. Trigger. Like the trigger found in Model 70 and XPR rifles, the Rimfire M. O. A.