I had talked to Al Nelson at NOE Molds last January, about three different diameters of molds, using the same cherry to cut all of them. It's done by interpolation on a CNC mill. He does that a lot in his mold making but, to date he only does it to fit molds to a basic groove size and increases diameter in .002 steps.

This is a basic 14 twist bullet length and will stabilize in all three calibers with that twist rate, 30, 32 and 33. A advantage to this is for the small groove 32's that more barrel companys are making, as the 32 design will be able to be had in .321 and .323 base bands.

The taper is only .002 on the chosen groove size with, a additional .002, to insure a seal at the breech but, depending on demand, the base band could be droped to .001 over groove, making it .003 tapered bullet. The .323 base band will cover a greater number of throat sizes though.

When I taked to him before, he told me that he only did .002 steps but, the diameter can start anywhere. One other thing that may be possible is the length could be variable from -.03 to +.02, by increasing or decreasing the base band length.

I want to see how much interest there is in this concept, I'll wait 1 week, if there is enough interest, I call Al again and finalize what will be the end result.

These are the three basic bullets:

What he is having done by the use of interpolation is in essence having the cnc mill machine a circle. In doing so, what he would do would be to hold the cherry stationary and then close the mold around it. That would give you a base size. Then the mill is told to machine a circle of say .001". That would give you a new cavity that is .002" larger than the original cherry.  CNC mills are wonderful creatures if you have someone that is good at programing them, and any more, the programing has become very easy compared to what it used to be. 
Hope this helps clear things up a little. 
Sam

Does he say anything about eccentricity? It's not uncommon for holes to out of round a thou when circle milled, due to wear of ways and ballscrews. The encoders on most cnc's are counting how much the drive motor moved, not how much the table moved. The only one I have ever used that was really good is an old Deckel with linear encoders instead of rotary. It would finish mill a circle to about 1/2 a tenth.

Frank-Interested in the 32 cal with the .321 base band. Thank You

I've interpolated before but didn't know it. Using a dividing head. Single point manual interpolation? 

      Joe.

For those that might be concerned about the spitzer nose, it should be at least as strong, if not stronger than the PJ noses. Compare the ogive length to the PJ. The PJ is .550 long and mine is .560 but, my meplat is larger by .013. The band sizes are also similar. So, it's kind of a modernized PJ and also very similar to the Ron Longs.

The other thing about this mold is the radi grease grooves, that also makes it stronger, overall.

Frank

What keeps the cherry from flexing by no longer being held to center by the two mould block halves closing on it? I fully understand the concept but what insures the bullet will be perfectly centered around its axis from nose to tail?

OkeyMaple PM Sent.

JLouis