Injecting into adipose (fat) tissue isn't the end or the world but surely isn't ideal. There is a higher likely hood that the depot will stay there longer because of much slower absorbtion time and you always risk it abscessing at the same time.
Realistically, it doesn't hurt anymore to penetrate the muscle than it does to get past the upper layer of the skin.
If you're using a needle that 'just barley penetrates the muscle' you're either too fat to be on gear, too stupid to learn proper injection sites (and shouldn't be on gear), or you're using too small a needle. Believe it or not, 1.5" 25g can be use to shoot just about anywhere if you're even decently developed. The deeper in the muscle, the better.
EDIT: 1cc isn't the end of the world 2cc+ could be dangerous as mentioned above.