Lapua 139 secant ogive specifications help?

[308nate]

I'm working on a program for single pointing a 260 chamber. I would like to match the throat to the secant ogive on the 139 bullet, but am having a hard time finding the ogive specifications and I don't have an optical comparator. any help would be great.

Thanks,
Nate

 

[watercam]

If you have a copy of Applied Ballistics laying around it is in there...

 

[308nate]

Thanks, but I don't have applied ballistics, maybe I'll have to get it. If anyone has the specs and would care to share them that would be great.

 

[dmoran]

Nate,

Here is Applied Ballistic's specs:

Lapua 139 Scenar

1.365 <> OAL
0.690 <> Nose L
0.200 <> BT-L
0.215 <> BT-D
0.075 <> Meplat
9.7 <> Ogive Radius (Tangent)

Let me know how the single pointing and the new tooling for it works out...
Donovan

 

[Erik Cortina]

I have asked this many times myself. "Why can't a CNC single point a chamber?" Looks like you and I think along the same lines Nate.

Good luck with your project, let us know how it turns out.

 

[dmoran]

I have asked this many times myself. "Why can't a CNC single point a chamber?" Looks like you and I think along the same lines Nate.

Eric -
Some BR shooters have been single-point cutting there chambers (and dies) for several years now.
Back in 2007, Phil Bower set the IBS1000 HV-Gun group record with a single-point cut 300-WSM chamber.
D

 

[308nate]

okay guys. thanks for the info.please forgive my ignorance but I still don't quite understand. I realize the ogive radius is .264 x 9.7= 2. 5608"
so what I don't understand is being a secant ogive what is it tangent to.or how do I reference my Arc Center.Thanks
Nate