Ah, I misread the original figures (0.0003-0.0004").
But... I agree with everyone else. A ridge of 0.0004" isn't going to make a difference in decent brass. Something else is causing the problem. In my opinion... the brass is bad (as OS stated), there's a die problem, or there's a variable you're missing in your reloading process.
Are the bullets seating crooked, catching case mouths, or out-of-round?
"Such is the strange way that man works -- first he virtually destroys a species and then does everything in his power to restore it."