With practice some people can rapidly change a standard magazine. https://www.youtube.com/watch?v=CAFxgQmxbGI https://www.youtube.com/watch?v=ksZqzPWm7VQ https://www.youtube.com/watch?v=W-6jXQ3FE4o https://www.youtube.com/watch?v=cp7MsUkO3sE