I'm looking into the posssiblity of raising some new apple trees from my old trees, and have a specifc question about propogating / increasing rootstock.

Lets forget the grafting of the scion for a moment.

The question is, lets suppose I can get hold of or buy a small quantity of rootstock, would I then be able to increase this stock myself. Put another way, if you plant some rootstock without grafting onto it I'm assuming it will grown into a bush / tree? I'm then assuming you could take cuttings / layering to increase stock.

Is this practical? I'm assuming one of the disadvantage is you need time (several years) on your hands for the rootstock to estabish to the point that it can be used to produce further stock?