Thanks for correcting my generailization of your statement DD.... if the fuse is bigger, the hole needs to be bigger.
For what it is worth, the 3/16 paper straws have fit nicely into the .200 hole. I havn't had any need to keep the vent hole spotless to get them in. I don't know why the hole doesn't seem to need to be bigger, but the straws slide in with no effort whatsoever. It is possible that paper straws are made to a tighter tolerance than cannon fuse.
I use a 3/16 brass rod for a vent cleaner/ punch.
Speaking of fuse larger than 1/8 inch, my understanding is that it is sometimes difficult to legally obtain. From what I gather, 1/4 inch or 1/2 inch fuse is considered "time delay fuse" and the ATF feels that it is generally used for purposes other than sporting use. The dealers will often want to see an explosive permit of some sort before they will sell it. I have seen exceptions to that statement... once in a while 1/4 inch fuse shows up on the pyro web sites for general sales, intended to initiate arial charges. In fact, at this instant there is some Chinese made 1/4 time delay fuse available on one of the pyro web sites. It burns at 3 seconds per inch, which is pretty slow for cannon use. It also costs 75 cents a foot, as compaired to under 10 cents a foot for 1/8 inch.
Im not sure how the ATF decides what is regulated or not, but it is probably safer to assume that 1/8 inch fuse is the easiest to get.