[Hectic]

When i used to run an m203 i couldnt find replacement rings and befor i figured out to use hairties or rubber bands i just used wads of paper towwel to hold the bbs in.
Also for a cool look when you shoot substitute one or two chambers of bbs with either crushed chalk or baby powder rolled up like a cigarette in paper towel with the ends twisted.
I used to take a whole sheet one of the select a size types cut it into four strips length wise and roll the powder up in it stick a bit of masking tape on the loose edge then cut it to length and twist the ends. Just make sure your up wind or you mah get a facefull of powder lol