I have never heard an argument for a flat based bullet having a better ballistic coefficient than a boat tail in the same caliber and weight. The flat based bullet WILL seal better and give less erosion than the boat tail, but the two effects are essentially at odds with each other, one bullet won't give both. I always like flat base small bore bullets for bench rest targets, but use boat tail bullets for longer than a couple hundred yards on most everything, particularly larger than 6mm or 6.5mm. My experiences are essentially the same as Joe's.