Breech seating?

[jonk]

I'm not sure I have any gun that would benefit from trying this but have a question on the mechanics of how it works.

I understand that you seat the bullet into the bore, then follow with a primed, charged case.

All sorts of issues jump up at me here.

Black powder- you are creating an air void between the powder charge and the base of the bullet; a no-no.

Smokeless- how does pressure build enough to get consistent results if there is no neck tension? Or is it only done with FAST powders?

Both- how do you keep the powder from falling out of the case? Use of a filler or wad would violate rule number 1 of fillers- a continuous column of filler from bullet base to powder with no area to jump- which could cause a rung chamber.

[mpmarty]

Jonk I used to have a BSA Martini 450/577 that was rechambered to 45/70. I used to breech seat 500gr cast boolits and then load a case behind it with nearly a full case of H4831 and a nitro card wad closing the mouth of the case. Worked fine. I had a wooden tool to "seat" the boolit into the chamber. I used LR magnum primers.

[HORNET]

The ASSRA members that we have on here may want to correct me on this, but IIRC, the powder is kept in the case by a wad or wads. The height of the wad column for BP loads is sufficient that it is compressed to some degree when the action is closed. Last time I checked, floral foam was popular for smokeless loads and again , the length was sufficient to have it in contact with the boolit base (to eliminate the air gap that could cause a ringed chamber) when the action is closed. Powders for smokeless loads tend to be on the fast side but usually there is a combination of high sectional density and low case volume that can take pressures up fast. The .32 Miller Short , for example, is a tapered down .357 case pushing a cast boolit of around 200 grains with AA#9 being a favored powder. YMMV.