for me, its more of a matter of awkward of asking my artist (i always have the same one) what size i need. im not looking for a ring, i has one of those already. im looking to get a bent barbell, and talking to some people, figuring out the size is supposed to be different from a cbr.Just go down and get a new ring, make sure that the threads are long, as short threaded balls can work off and then they can get lost. I have had them fall out whilst wearing boxers and shorts, hit the hard floor with a ping.
I would guess if you have been wearing a 6 gauge for some years, that you could move up to a 4 gauge with out any problem. A curved barbell is easier to take out than a CBR, also look at a horseshoe... I move between a 2 gauge and a 0 gauge depending on how I am feeling.
I also don't want to go to a 4 gauge. 6 is big enough for me, and mine was never done with the intent of getting a large guage