Using some of what I've learned from cast bullets, I'm writing Dave Corbin to find out about making a 30 caliber die set having a long bore riding nose section.
The .308 base being, say, 1/2 inch long then a radiused step down to .305, with a taper to .301 with a spitzer or round nose tip. This being a bullet weighing 180 to 200 grains.
Aside from me wasting my money what pit falls do you fellas see here.
Jim

Arky - Just a thought with nothing really to back it up, but would such a bullet cause higher chamber pressures simply by virtue of the fact there is more and more of the bullet scraping against the barrel?

There is a VAST difference in the amount of force required to get a 150 gr cast bullet down a barrel and a 150 gr jacketed bullet down the same barrel. I learned this the hard way.

Pecos
My thought was just the opposite. I'm just pulling numbers out of the air here. Lets say the 180 grain round nose Speer/Hornady/Sierra has one (1) inch of bearing surface. My definition of bearing surface is that portion of the bullet that actually engages the rifling.
If I were to reduce the length/surface of the bullet that actually conforms down into the rifling, I would think I'd reduce the pressure required. The bullet front half would be riding on top of the lands with a slight taper into the larger portion that is actually fully conforms into the rifling.
This reduction in bearing surface may require that I use more of the same powder or a faster burning powder to achieve the same pressures and velocities.
What I'm hoping to acheive is a higher velocity with the same charge, since less energy is being lost to friction and deformation of the bullet into the rifling.
Jim

Arky - It is looking like I misunderstood you. I "misunderstand" a lot as I grow older. Probably we are thinking the same thing and I'm too dumb to know it.

Pecos
My two favorite sayings
Of all the things I've lost it's my mind I miss the most!
It crossed my mind, a short trip, you know.
Jim

You might consiter making a bump die and a current bore ride bullet. A little bump will change the shape true up the base and in a lot of cases improve accuracy, or make it work better in a certin gun. May they all be X's. SLW

Look at bore ride bullet dies. I think that is what you are asking about and can be purchased from stock. You run the bullet as far in the die as you want to be smaller and set the die at that depth. This way you can vary the abount of bore riding section you want. Good luck. Packrattusnongratus.