While I was up in Alberta last week one of the local guys wanted to show off his new Sako 7mm STW. He had only fired one round through the rifle since he had bought it and had a new box of Winchester 150 grain factory ammo with, he stated he left his Remington 140 grain ammo at home so we'd shoot the Winchester stuff. We setup a target at 100 yards at sighted the rifle using two round strings. it took two strings to get the rifle sighted to zero at 100 yards and I had then shot a string of three rounds. Keep in mind that these were not rapid fire sequences and we walked to the 100 yardline to examine the target after each shot string. So far we had shot 7 rounds through the rifle in this session. The owner wanted to try the rifle at 100 yards so he commenced with a three shot string, the third round in his string caused a puff of smoke to exit through the action of the rifle and upon examining the brass we found the primer pocket had blown out and the primer was laying loose in the boltway. We were a bit suprised and chatted a bit about how this had happened, ww decided that he didn't 'ccok' the round and the rifle couldn't be too hot to shoot as it was barely warm to the touch. The ambient temp was mid to upper 60's and there was a fine mist type rain so the rounds didn't heat up in the sun. We decided it was a fluke and moved the target to 300 yards. His first three shot string at 300 yards was pretty uneventful until the third round when we tried to eject the round...the bolt was solidly stuck. All three rounds were on target albiet a bit high and left. We retreated to the house where we later got the bolt open but found that the ejector was blown loose from the bolt and was stuck in the action. All this with factory ammo and a new rifle. The rifle will be taken to the shop where it was purchased for an inspection and repair(s) Any thoughts on what's up with this.