HD - The method you describe will work if you establish a weight proportion for the two pieces (stock + action and barrels + forearm). You must weigh and balance the whole gun and each of the two described units. Then you must compare overall balance, compare for each unit balance to overall balance point, and weight proportion.
I'll run a few tests and see how this works out.
I've dug through my (sadly limited amount of) books. One of our shotgun gurus, S.A. Buturlin, states the weight of the complete gun ought to be 2.0 to 2.2 times the weight of the barrels (without foreend). Another expert believes the weight of the "rear end" devided by the weight of the "front end" should give anout .995 to 1.005 ratio. (I can't say if these ratios were invented by the respective authors or picked up from W.W. Greener or somebody else.)
The obvious guess here would be that if a shotgun must have some weight-forward and still feel balanced, the barrels+foreend should weigh a bit more than the rear end, yet balance at the fron-hand grip spot (BTW, I think the "grip spot" for the front hand should be determined by the middle of the palm)
I can hardly wait for the results of the tests
