Wanting to try out coated bullets in order to save some $ vs the Montana Golds I've been shooting, I ordered a 500-round package of 124 grain round nose from Acme - I thought that'd be enough to get a good feel for whether I liked them, but not so many that it'd be wasteful if they were workable but not great.
Unfortunately, no matter what OAL I seated them to, I couldn't get them to pass the plunk test. I also had what I felt was an inordinately difficult time getting the bell and crimp set such that the coating wasn't getting cut/shaved. After much frustation, I decided to measure the bullets, and it turns out that instead of the .356" that they're advertised at, the bullets were .357" in diameter. (I'm fairly certain that my calipers are accurate, sincy my supply of Montana Gold bullets measure the .355" they're supposed to.) My guess is that that's why I couldn't get them to plunk at any OAL from 1.16 all the way down to significantly below 1.08. (I stopped measuring after a 1.08, but I shortened the OAL several times after that measurement, and they were starting to look like .380 round nose.)
I used the contact form on Acme's website and told them my story. Hopefully they'll have something useful to say, but I'm curious whether anyone on the forum has had a similar experience at some point, and if so, what the end result was.