Back to arowhead's problem...
Are you sure you don't have an AR-15 mag? I haven't seen a mini mag that says .223 on it but I think I have seen it stamped on AR-15 mags. This could be the reason it does not fit in the magwell, but still holds .223 bullets. Admittedly, I have never tried to fit one of these into a mini, but I know they don't usually fit. (I bet Ruger could have sold alot more minis had they designed them to use AR-15 mags. Part of the gun's appeal is that it can use cheap military surplus ammo. It is too bad that isn't the case for its magazines). Anyway, if that isn't the reason, you probably just bought a real peice of junk magazine.
Are you sure you don't have an AR-15 mag? I haven't seen a mini mag that says .223 on it but I think I have seen it stamped on AR-15 mags. This could be the reason it does not fit in the magwell, but still holds .223 bullets. Admittedly, I have never tried to fit one of these into a mini, but I know they don't usually fit. (I bet Ruger could have sold alot more minis had they designed them to use AR-15 mags. Part of the gun's appeal is that it can use cheap military surplus ammo. It is too bad that isn't the case for its magazines). Anyway, if that isn't the reason, you probably just bought a real peice of junk magazine.