I recently ran into an issue with a batch of 38 wadcutters that is a new experience. About 40% of the loaded cases have a bulge at the base of where the bullet seats in the case. I know many rounds will have a slight deformation (that's what holds them in the case) but these are not anywhere close to chambering in any of my 38s. I have loaded many other bands of lead wc and swc, jacketed etc. without ever having this issue. I tried different cases (brands) +P, non +P, brass and nickel cases...I'm at a loss. I do not have a good micrometer but my calipers show the bullets at .358 to .3585, within the same range as other rounds I load without problem. The bullets are BBWC, not hollow and are really hard. I'm wondering if it is because they are so hard that this is perhaps the issue. I called the manufacture and they said I could send them some sample unused rounds for them to mic but they basically said that it must be something I'm doing. They could be right...but it only happens with these loads, not the previous 10,000 or so in 7 different calibers. Any suggestions are welcome.