I've done an H&R Handi-rifle 30-30 Improved by hand, it's important to make sure you stop reaming when the rim cutter on the reamer just touches the existing rim cut or you'll cut to far and end up with an unsupported shoulder which may result in split necks when fireforming factory spec ammo, it may happen anyway, it just depends on the original chamber, if it's on the tight side, I think there would be less of an issue, on the large side tho is where there may be a problem since the barrel can't be set back on the fixed barrel TC. You can solve the issue tho by simply necking the brass up, then partially full length sizing just enough to push the shoulder back to zero headspace or loading to a longer COL so the bullet is into the lands when chambering the brass, then fireform.
It's important to make sure you don't put any side pressure on the reamer so you don't end up with an egg shaped chamber, I use a nut driver on the reamer instead of a T-handle, then you're twisting the reamer instead of levering on it from one side, mount the barrel vertical in a bench vice and use plenty of cutting oil, remove the reamer and clean the chips out every few turns, never turn the reamer backwards.
Tim
