Yesterday me and the wife was shooting and had a misfeed in my ar15 shorty. Don't know how it happened. The bolt was jammed 1/3 of the way back and I couldn't unjam it.
Finally I got the sucker back and out popped a bullet, primer was not hit, and the bullet head was stuck down the neck of the case and just the tip was sticking out.
Question, at what point,if any will the case go off from being too compacted?

It won't.  It sounds like the round slipped out of the mag and got hung up above the bolt carrier.  Mark this mag, and if it happens again, replace the follower and spring.