It leads to problems because reloaders either make mistakes by overcharging their loads, which can lead to many issues. However, most quality 2011 makers make good firearms, and at the end of the day, it's the responsibility of the user to take care of his open platform and ammo. Some like to reuse brass, others like brand-new brass. Personally, I've never had any issues using once-fired brass. None of my open guns have malfunctioned, broken, etc. Many shooters usually have a "backup" gun, but it's not truly needed if you're not a serious competitor.