I was going to try the soda straws, but never found any large enough. I wound up getting 3/8" PEX pipe at the hardware store, plugging one end and whittling down the other to form a cone. cut the PEX into sections long enough to hold 10 rounds (my range has a 10 round limit). load em up and plug the other end with a foam ear plug. they work real well, but they do take a try or two to get use to loading. I did dump one tube on the ground. another time I loaded one round upside down and that mucked up the works a bit. I have enough tubes to hold 140 rounds and plan to make six more so I can load 200 rounds before I go to the range. The tubes do make it simpler to load at the range, time will tell if I keep using the tubes, or just go back to loading one at a time, but for now I'm sticking with the tubes.
I have end elsewhere that folks use aluminum arrow shots for the tube. may try that as well