Before you order a tuner measure the last 2-3/4 inches of your barrel then go to the Lilja Barrels website and calculate its weight.
Now multiply that weight by 1.5 and have your tuner made to that weight.
To get a idea of where the mass of the tuner should be in relation to the bolts face look up The Purty Method by Tony Purty so you get the weight out in front of the muzzle the right distance.