My loader will generally throw within 0.2 grains of the average throw for that bushing and powder. If your loader is throwing a spread of almost 2 grains, then something is wrong somewhere.
Here are a few suggestions of things to check.
Do you have a powder baffle in the powder tube?
Is something clogged up in the powder bushing or adjustable charge bar or powder drop tube?
Is your reloader bolted down tight?
Do you have a lot of static cling of the powder to the powder tube?
Does the reloader move through the cycle with reasonable smoothness, or is it rough and jerky?
Something is apparently loose or is varying way too much from throw to throw. A variation of 2 grains from high to low is not normal or acceptable, IMO.