I cast for the 348 Win and once you work out your chamber limitations it's no different to any other calibre. I've got two CBE moulds, both GC designs. I've also patched 338 cal PB cast bullets successfully. This FN design was meant for the 33 Win with a nominal weight of 200 gr.

The Browning I have has no throat at all but the chamber neck is a little long, which might give the impression of a very shallow throat. Both CBE designs foul on the end of the chamber if crimped into the crimp groove. However I use a Lee FCD to crimp the bullets where they will feed, cycle and chamber freely.

I found the heavier CBE mould to be quite accurate, even with the GC sitting below the neck line. The load I developed was using IMR 4064 (old tin). 47 gr worked well and these chronied 2150 fps. I could have gone higher but accuracy fell off. I might try a slower powder next time to try to boost velocity (with accuracy) to develop a load that prints nearer my jacketed load.

The patched 338 cast pill worked well too. I used Veral Smiths glue on patch technique and while time consuming it did work well. In this technique sticky labels are cut to size and stuck on to the bullet. After letting them 'set' for a few days I ran them through the lube sizer (0.350) and then loaded them as per any other cast bullet. I pushed them to near 2400 fps and accuracy was great. A load of 50 gr IMR 4064 produced an accurate load that printed close to the jacketed bullet load I use.

For very light loads you could also size down pills designed for 357 pistols too but haven't got around to doing any of this.

Someone passed on to me a spreadsheet with 348 load data gleaned from a number of sources. If anyone is interested in a copy send me a PM with your email address and I'll forward a copy.