Well, 4.4 is a full power load, so a double charge would do it. I use a 550, and because you have to index it manually a double charge is certainly possible. IMO you must absolutely positively only ever stop AFTER indexing. That way, if something interrupts you, you've already moved the cartridge on and a double charge is impossible. If you stop without indexing for any reason, and then come back and crank the handle a second time, you have a double charge.
I also leave the die station after the powder measure empty and eyeball the cartridge as I place the bullet into it, to verify the amount of powder.
They say there are only two types of reloaders: those who have had a double charge, and those who haven't had a double charge YET, so don't feel too bad.
Just make damned sure it's your last one!