S&W Fan
.450/400 Nitro Ex
Don't really feel like cracking open my rifle every time , so I'll just take the few extra seconds it will take to load the mag loader.If the SHTF, are you keeping the magazine locked? If so, buy a few of them.
If not and you will be using it only for the range and you only have one or two, it is faster to just load the fixed magazine rather then loading the loader and then the fixed magazine.
This device only works if you have lots of them to save time. IE at least 15 of them to fire 150 rounds at the range.