Well, as a "trained and experienced" police officer, he should be more aware than anybody else that " Every gun is always loaded, even when it's not "
He should have check the chamber while not even consciously aware he was doing it. It should be an ingrained habit. Almost instinct like in nature.
I check all guns when handling them even after being showed it is empty.
However. The store is just as at fault in this situation.
I know to check as well as most who are members of this site, but that doesn't let the gun store off the hook any more than saying that if I was really defensive driving...I wouldn't have been hit by a drunk driver.
In today's world with ever increasing people buying guns to defend themselves, with more and more first time buyers picking their first guns and first concealed carry guns...the odds of unexperienced gun owners ( who do not practice safe handling ) getting hurt is higher and higher.
At the very least, the police officer is stupid and careless. He is lucky that somebody wasn't standing beside him and got killed.
The store is lucky nobody got killed.
The blame is shared 50/50 with each party being 100% responsible for their share of negligence.