Beretta 92sb question

[jegmpa]

I just picked up my first handgun. I purchased a preloved beretta 92sb. It was previously a law enforcement handgun. I am fairly new to guns and just took it out to the range tonight. When i got the gun i bought a new factory magazine and found that the cartridges stuck a little. Is that normal? The two "used" one fired perfectly and i had no issues at all with it. Is there a wearing in period for the magazine?

Thanks all!