Don,
I'm not sure about all of them but there are many that slugged out to .432" or so. Unfourtunately mine is one of those over sized bores. I have not had any luck with this barrel. I would come across a really good load, or so I thought, and then the next trip to the range would end up looking like I was patterning a shotgun instead of shooting groups. I have yet to get hold of some oversized cast bullets to try out but I did try some of my home cast bullets that had been left unsized with only marginal luck. I am nearly ready to chuck the whole thing.
There is hope though, I read a posting here were someone just slugged the new .44 they got and it turned out to have a groove diameter of .430" so maybe they're getting closer. As for the twist, I think it is still at 1 in 38". I had a lot of help here at GBO from all of the guys on the forum and I spent a lot of time and money with no results. Read some of the posts that have been up on the forum and they will speak volumes. If I were you though I would wait until NEF gets it right and comes out with the proper bore dimentions and a better twist.
As always, Quick will have more and better answers than I and he is a whole lot more up to date with what NEF is putting out so I'm sure that he will weigh in on this as well.
Best of Luck,
Wolfgang
