Grey HawK : For best working result, your jag needs to be .040" smaller than the bore diameter, in order to allow the cleaning patch to blouse out, and be grabbed by the grooves in the jag. The patch then puts enough material down into the grooves to get into the corners, and PULL out the crud.
When I run a patch down my barrel, I don't try to set a speed record with one long stroke. That is how Ramrods get bent or broken. I do a hand over hand, pulling back on the rod a couple of inches every 8 or so inches, and work my way down the barrel to about 2 inches in front of the breech. I amy stop sooner if I feel the patch is getting " Gritty " as it goes down, indicating to me that the patch is loaded with residue, and I am no longer pulling any new residue out. When that occurs( usually on low humidity days) I will pull the rod and jag out of the barrel, and check the cleaning patch's condition, and either flip it over, or get another patch to finish going down the barrel. I try NOT to push residue into the breechplug face, as it cakes there, and is very hard to clean off, even after soaking the barrel with moose milk. You end up having to use a scraper on the end of the ramrod to scrape the darn stuff off the face.
If your jag is too big, then you can chuck it in a drill press, or even a hand drill held in a bench vise, or by someone with very strong hands, against a table, and use a file on the brass jag to reduce that diameter a few thousandths of an inch. Jags work best if they are graduated, or stepped from one ring to the next, with the largest ring at the front of the jag.