Pugachev Cobra
I once owned a C-210 and was programing a small computer to do weight and balance for various fuel, passenger, and bagage loadings. Using the latest weight and balance info for the aircraft, I kept finding that what should have been perfectly reasonable loads were giving me a CG out of the aft limit.
I audited all the weight and balance changes since the original factory weight and balance. On the 5th weight and balance form depicting changes in aircraft equipment (of 8 such changes), I found a transposition of digits in a moment calculation. After correcting that error and all subsequent calculations, the aircraft CG was well within limits.
Light aircraft are rarely re-weighed unless they require major repairs. Current weight and balance numbers are usually the result of a chain of calculations by various mechanics adding and removing equipment. All you need is one mathematically challenged person in this chain to have problems with your weight and balance information.
On the Arrow with the forward CG question, have you observed handling problems such as higher than normal nosewheel liftoff speed compared to POH data? If so, it points to an actual CG problem, if not, more than likely a weight and balance calculation problem.