A little bigger, eh ? I just measured the Baron and compared it with a Jr Gent II. At the point just behind the ridge at the top of the 0.43" long nib section (the Baron is hexagonal there) the Baron is 0.325" thick maximum, whereas the Jr Gent II (it is round at the same point) is 0.320" thick. Seems like a pretty common size.
I just tried writing with both and I agree with you that a little fatter would make it easier to grip. The fact that the Baron is hexagonal there (0.300" thick minimum) makes matters worse.
If you go to the full-size Emperor, the measurement is 0.39" (round). That's not in the same price range though !! I don't have any intermediate size pen readily available.
Edit: Oh, I just found one ... the El Grande is 0.39" and is in the same price range as the Baron but maybe not quite as nice.
Bear Tooth Woods - El Grande Fountain/Rollerball Pen Kits
https://www.arizonasilhouette.com/c...=7fccfc42f7935da6750efa7578e34262&Screen=SRCH