I have force fed many corn snakes over the years and some come around and some don't but at least I tried. Force feeding is a last resort but you have to do what you have to do, hell I fed a hatching undersized hondo milk snake for almost 9 months weekly with a pinkie pump before it finally just gave up. Sometimes you have to put in alot more than you will ever receive.
Force feeding a snake is stressful but I imagine starving is no walk in the park either...
