I'm taken with the notion of building a double .45-70 for a first project, simply for the cost of feeding. I've read and reread the thread on the CZ actions, and am satisfied that they will meet my needs, but still have a couple of questions. I noticed that the Coach gun from CZ has the same third bite as Tecnos donor gun whereas the Bobwhite model has the Greener topbolt. Do most of you experienced hands feel that this third bite is sufficient for the cartridge or should the Greener be leant towards? I intend to load BP or nitro for black loads. Ellis Brown recommends to compare doubles for proper frame/cartridge proportion. Unfortunately there aren't exactly racks full of rifles to compare around here. I understand that more is generally better particularly with chamber walls, but are 16 bore dimensions sufficient to the threaded barrel technique or go all the way to 12 bore?

I really like the idea of ears on this project if the third bite like Tecnos shooter will work but that would go straight to 12 bore.

Thanks in advance for your input. I need to justify the countless hours I've spent perusing these threads! LOL