Justin,
Placing anything in the case CAN result in chamber ringing. It doesn't matter what it is. The problems with Dacron (or anything else) arise when people place a small amount in the case to hold the charge back with airspace between the filler and the bullet. When the powder is ignited the filler is propelled into the stationary bullet which acts like an obstruction and the filler is forced to move outwards causing the ring. If you choose to use filler (and there are situations where you have to) you MUST completely fill the air space in the case with the filler. Doing it this way results in a progressive amount of force being placed on the bullet as the filler moves forward. This eliminates the problem of the filler gaining momentum and then impacting the bullet which causes the ring.
What exactly are you loading for? If you're loading for a single barrel rifle you have more options than if you're loading for a double as you don't need to worry about regulation. Many black powder cartridges can be loaded with 5744 or Trailboss with no filler needed. If you are loading for a double though you may not get it to regulate with those. If loading nitro for black (NFB) loads in a double, IMR or H4198 with filler is a standard loading that's used by many many people (including myself) with no issues in rifles that cost more than most cars to replace if damaged.
If you're loading full nitro loads in a double rifle you can usually use IMR or H4831 without filler. There are exceptions though and the 450 and 475 3 1/2" Nitro come to mind. There is just to much space to get reliable ignition without a filler. Even when you can get away without a filler many choose to use RL15 and a filler as it results in less perceived recoil. This is not something only done by a few, it's common in the world of nitro double rifles. It's the way Kynoch chose to go when they reintroduced nitro express ammunition. They even sold cut up backer rod for others to use in reloading.
The internet is a wonderful place to get info but you need to be wary of where it comes from when everyone has a voice. It's worse when you don't ask a specific enough question and others speculate.
