Regarding your question. The 6x284 allows you to shoot the heavier bullets faster than either the 6BR, 6BRX, 6mmAI, and 243AI. The 6x284 gives you more power, for kills, at longer ranges and bucks the wind better too. The other 6mm's, I mentioned, are all awesome for varmints. They each have their + and -. I just perfer the 6x284, because it has more punch down range. However, it is harder on barrels.