There are several well known secondary rifle and pistol magazines, but Factory magazines are usually the best to obtain.    Factory magazines are made by the companies that manufactur the firearms and that’s usually where you’ll get the best magazines.   There are exceptions to the rule with rifles.   Magpul isn’t making firearms, but they do one heck of a job of making a reliable and durable rifle magazine.    Sturm Ruger is the largest firearm manfacturer in the United States.   They make more guns and sell more guns than anybody else.

The Ruger Mini 14 is a rugged and reliable 5 shot carbine and there is still much debate about which magazines feed reliable.   Ruger is now selling 20rd magazines to the public which they did not due for decades.   The Mini 14 was the gun that suffered more under the Assault Weapons Ban passed in Congress in 1994 than any other firearm IMHO.   Everyone seems to want to make this gun and assault weapon, but the reality is the 5 shot Carbine spits a lethal round, but your safest bet for most purposes is to keep the Ruger Magazines made by the factory around since those are defanitely the most reliable.