Just the thought of doing that gives me the hebe-gebes, and my skin is still crawling form cracker's writing it ten times.
All that said I don't really thing there would be enough force in just the slight spring tension to ever set off a round even if the rifle was dropped from a height. If you think the force the spring puts on the the firing pin when the sear is tripped it would have to be EXTREMELY greater than the slight amount of force from the tension on the spring from the primer forcing back the firing pin. Also, the spring would in fact act as a damper absorbing shock like in the suspension of a vehicle.
So, thinking of it technically it seems like it would probably be safe. I WOULD NEVER DO, OR SUGGEST, OR CONDONE SUCH ACTION, but i doubt very seriously if it is likely a safety issue.
I know I'm gonna catch he-double hockey stick for this, but remember I said I'd never do, suggest, or condone it.