Interesting, Dom.
One thing (If I'm understanding your design correctly) that might be a problem with a fixed firing pin machined into the bolt face is that before it fires, there will be a gap (the length of the firing pin) between the 'cartrige-sleeve head' and bolt face. At the moment of firing, the front of the cartrige-sleeve will want to blow back, possibly opening a gap between the rear of the barrel/front of the sleeve. That could cause rapid fouling of the gun. It may also want to blow the primer from its pocket somewhat.
Or maybe not.... If it fires precicely as the bolt face contacts the rear of the sleeve it shouldn't be a problem.