I have a new in box model 14 with a detachable magazine. When cycling the bolt forward, about every fourth round pops out of the ejection port. The bolt engages the rear of the cartridge and pushes forward as expected. But, once the cartridge clears the lip of the magazine it pops out of the ejection port. Usually its just the rear of the cartridge that pops out. This has happened with several kinds of factory loads. Thanks for the help.