I have a RCBS lockout die. In theory, these will only check for double charges and no charges. However, I have found they have a range that I think would be powder dependant, with bulkier powders allowing for more "wiggle" room for fine tuning. With denser powders the delta between a proper charge and a double charge would be much less.
I currently am using one with a 4.8 gr charge of 700X, which is quite bulky, and found it will "Lock Out" at about 6.3 grains or 31% overcharge. You can fine tune it more if you like, but if you crank it down to trip more quickly for an overcharge it will allow more of an undercharge.
I still look in every case before I seat a bullet.