Design, Keith vs ?

[Changeling]

When you look at two designs such as a Keith design with the "shoulder" ahead of the crimp groove and the LBT with no shoulder. I am assuming that the LBT bullet has a diameter that is relative to the groove diameter in the area that the Keith shoulder consumed. If this is correct, how do you know the amount of forward linear (from the crimp groove) bearing surface?
This is assuming you do not have a fired projectile to measure.

[GLynn41]

--are u asking --excuse my ignorance -- about crimp to nose or bearing surface- anyway both of those the mold maker can tell you and answer this one too I am sure
the two LBTmolds and a Mountain Mold and a Miha mold I have --the engraving of the rifling starts above where the front shoulder would be in a keith

[RobS]

The shoulder or front drive band of the Keith bullet is same diameter as the rest of the bullet's drive bands........or at least it should be. The LBT LFN/WFN designs should also be the same in that the diameter of the front drive band (area above the crimp groove) should be the same as the rest of the bullet’s drive bands as well.

In other words:
The front drive bands on both bullets are full diameter. The Keith's front drive band is simply very apparent where as the LBT is less so since in works into the nose of the bullet.

Without a bullet in front of you, your best way to figure how much of a front drive band there is on the LBT LFN/WFN is to call up Veral Smith and ask him. Should you have a bullet then you can size it and see where the bullet sizes at on the nose to determine the front drive band length. Designing a LFN type bullet on Mountain Molds web design you can actually specify what front drive band width you want. I am certain you can have any custom mold maker do whatever it is you want and they will also have knowledge on whether your idea is a good one or a poor one.

Hope this helps you out.

[Changeling]

That tells me what I thought, but wasn't sure. I never stopped to think about sizing the LBT type bullet to see the sizing marks on the nose. Thank you.