I make my own dies for a lot of things, but I have never YET tried making a bullet "pointing-up" die.

If a guy wanted to make a bullet which fit the throat of an existing chamber,could he make a point-shaping die ("pointing-up" die) by using the same reamer he used to cut the chamber throat (bullet-seat)?

I have some older reputedly Red Elliot 9-reamer sets where 5 or more of the reamers are shaped to make bullet seats which exactly fit the bullets to be used in the gun(s).

Seems to me if I bored the die cavity part way (the part with parallel sides), then finished the cavity with the same die used to cut the bullet seat in the rifle chamber, a guy might be able to make bullets that really would fit his rifle(s).

I have already made several bullet base "plungers" (for lack of the correct term which escapes me) to bring other old die sets back into use, so am familiar with that part of the process. Ditto bullet ejection pins and auto-ejection systems.

Okay tell me the 87 reasons this hair-brained, gray-cell-flatulence won't work.

Understand that I have never made a jacketed bullet, just resized a few, but I would guess that your bullets would be undersize because of the springback. I would think the die would have to be a bit larger in diameter than the desired end result, unless you were starting with bullets that are already oversize. This making any sense?
C.G.B.

The "bullet seat" reamers cut very slightly oversize, as they need to...to keep bullets from sticking in the chamber when one decides to extract/eject an unfired round. Othewise the cartridge cases might extract but the bullets might not, leaving them stuck in the chamber once in a while.

If the bullet-seat reamers didn't cut a bit oversize, one might well want the bullets very slightly undersize, for the same reason.

Lastly, when using lead cores, I wouldn't think the jackets would be springing back any significant amount. As the bullet core is expanded (swaged up) to fit the die cavity, the jacket does spring back to tightly grip the core, but it doesn't spring back to a size smaller than the core...or at least I wouldn't think so. But then, maybe I am wrong again. It sure won't be the first time....

I KNOW this can't be as simple as it seems.... What AM I missing here?