If you're referring to stove piping as in the photo above - happening with a bolt action rifle - I've had that happen with my .243 when I first put it together.
It needed a little "tweaking" of the mag feed lips. When the mag was full, upward pressure from the spring was a bit more than the mag lips could hold. By closing them a bit, the round stopped jumping out of the mag as soon as pressure from the bolt was applied.

It took a little observation & adjustment while loading the mag & chambering the first round. I made up some dummy rounds to avoid accidental firing & blowing a hole thru the garage refrigerator. Again.