Sub MOA groups can be hard to achieve without consistancy at the bench. Little things like cheek pressure on the stock, where the forearm rests on the bags (I presume you are using a sandbag or some type of padded front rest), and the rifle itself. Some rifles just won't shoot 'tiny' groups and some shooter think every rifle should shoot 1" or less. Some shooters won't agree with me but I don't like the pressure point Remington puts in the barrel channel, especially if the rifle isn't shooting well. And this may be your problem not being able to watch your bench shooting technique.You may be varying your stock location on the front rest changing the pressure on the barrel.
You said you clean your rifle. Thats a start. I' wondering if it could be a bedding problem. A simple check that my local gunsmith showed me is this: Take the screws out of the stock and remove the action. (this is good to do occasionally to clean the underside of the action/barrel and wipe off the stock). Replace the action andsnug up the front screw. Do not make it super tight. Then put in the tang screw and as you tighten it up, watch the point where the barrel meets the forearm end of the stock. As you tighten it, if the barrel starts to lift away from the stock, there is something wrong with the bedding.
But, before you have any work done on your rifle, on your next shooting session, make a conscious effort to make all your shots the same. Place the forearm on the bag in the same location, Use consistant cheek pressure on the stock, same grip tension, smooth trigger squeeze, etc.