Over the years I've loaded several thousand 9mm 115 gr jacketed bullets on my Dillon 650. I use a very mild taper crimp, just enough to take out the slight belling I use. Within the last thousand rds, I've started getting scratches near the mouth of the case where the taper crimp die squeezes out the belling. The scratches are showing up in the first 3/32" by the mouth, they are not huge but deep and sharp enough I think they will eventually start cracks in the brass. I used a .45 stainless brush in a straight cleaning rod, chucked in an electic drill, to clean out the crimping die. That solved the problem for only about 50 rds, now it's happening again. What's going on that I loaded about 5,000 rds in previous years without the scratches, now it looks like I need to clean the crimping die every 50 rds or so to prevent scratching?