Using the exact same sns 147g minor loads I have had to use .245-.265 front sights. On all glock 34 gen 4 with same rear sight. Each glock is a little different and whenever I get a new one or change loads I take them to the range and sight them in. If high or low of aiming point I use the Dawson sight calculator as mentioned and buy the appropriate sight as a front sight is less than one trip to the range worth of ammo.