I think it will work too. Looks nice. It appear you used a lathe to bevel the chamber at the mouth. Is that how you managed such a nice fit? Seems you would have had to turn the hole some or the round some? Perhaps you were able to use a 5/16" round and a letter P drill?
Just so you know, now that you have the breech plug looking like it does, a 0.028" hole is large enough to provide reliable ignition in sub-zero weather of BH powder. That way, you can have more shots as the hole erodes. Another thing that is helpful, is to increase the size of the flame channel from 3mm to 5/32". Sabotloader first showed us this a couple of year ago. What this does is reduce the pressure on the primer. This also allows more shooting before the flame channel gets clogged by burnt carbon.
Hopefully you don't think me presumptuous making these suggestions; obviously you don't need my help to make a nice looking breech plug. Your work looks as though it were done by a real machinist, not a carpenter somehow getting by.