Agree totally with Rick. Any rifle under about 8 pounds you better hold onto while shooting. I just worked up loads for my buddy's Montana in .308, 130 TTSX powered by AR-Comp, three shots pretty much touching. My 8400 Montana in 300 WSM shoots great. My Howa Alpine which is not quite as light, shoots well under an inch, Howa Superlite which weighs less than your Montana also shoots very tight groups. I use a Caldwell front rest and a bag at the back, shoot three shot groups, grip the pistol grip firmly and either lay my hand over the scope or grip the fore end securely. If you shoot a light rifle like a heavy rifle and just rest the fore end and buttstock and hardly grip the rifle when the shot is fired, the gun will move before the bullet exits the barrel. My 2 cents.