For quite a while I've had a box of bullets that are 300gr, .512" diameter. I've been wanting to try a 300gr bullet in my Uberti .50-95 model 1876 Winchester, but I need a .515" bullet to fit my barrel. I came up with the idea of using a .515" sizing die and an arbor press to enlarge the bullet's diameter .003" by swaging it.
As you can see, the bullet started out .512" diameter.
I placed it into the die, base down and set it in the arbor press. I used a 1/2" fine thread bolt and nut to adjust how far down the hullet would be pressed. But first I made sure the bottom of the bolt was perectly flat. The nut is adjusted so the bolt will press down on the bullet about .030", then stop. The nut is loctited in place.
Using an arbor press I brought slight pressure to bear on the plunger, pressing down until the nut stops against the top of the sizing die. This expands the bullet from .512" to .515" die. Then I then flipped the die over so the base of the bullet was up. I used the die's original plunger to push the bullet back out, ensuring it was sized evenly.
I then measured the bullets and they were at .515". I did 20 bullets and all came out with their length within .001".
A couple notes:
1. The lube holes in the die must be above the area of the driving bands, otherwise lead will be extruded out the holes.
3. The bullet is .030" shorter now with a slightly wider meplat.
Now I have some .515" 300gr bullets to try in my rifle. I'm sure I'm not the first person to do this, but it was a new idea to me. I hope ya'll find this useful!