So here is a link to download the original MS Excel spreadsheet for Nose Cone Design.
I use a modified version myself to plot shapes that resemble long range target projectiles. If I can do it I’m sure those of you some knowledge of spreadsheets can come up with their own modified version. Follow the instructions and enjoy!
So if you’ve managed to magnify the outline of your ogive, effectively you can calculate the radius by measuring the meplat to the shank/ogive intersection. This will become your chord length W.
The Sagitta of the arc or height (H), is measured perpendicular from the midpoint of the chord W.
For double or multiple radius ogives there will be multiple chord lengths measure. Note also this method only works with ogives using a tangent and secant radius. The larger your outline is magnified the more accurate your measure will be, useful for those of us without an optical shadowgraph comparator or other such metrology equipment. Remember though you may have to contend with the parallax error depending on how you capture your image outline.
Precision gilding metal match grade target jackets
+99% Lead (Pb) cores
Hand swaged in Australia
The G7L series of projectiles is Antipodean Industrial’s entry into the hand swaged projectile market. In principle, the G7L is a traditional long range (300y+) projectile designed for high levels of accuracy while maintaining supersonic velocity levels.
So why is the first projectile series called – ‘G7L‘?
The ‘G7‘ part of the name refers to the preferred standard of drag curve, used to compare the form factor of a long range boat tail projectile, to estimate its ballistic coefficient (BC) at various velocity (and atmospheric conditions). Traditionally a G1 drag curve was used to perform various ballistic estimates based on the Mach number measurement (velocity including atmospheric conditions). The shape of the projectile used to create the G1 drag curve had a flat base and an ogive profile similar to a benchrest projectile. It has been found that the G7 drag curve more accurately predicted the various ballistic calculations (e.g. trajectory/velocity) at longer ranges. This is because the G7 drag curve was developed using a projectile with a boat tail and a more aggressive ogive profile; hence a closer representation to modern long range projectile shapes.Modern ballistic software is now available with BC calculations utilising the G7 drag curve as an option.
The subscript ‘L‘ is acknowledgement of my bullet mentor Mr Gary Little for his assistance in developing this first range of projectiles for Antipodean Industrial. Gary Little produced a wide range of hand made custom projectiles under the company name of Little Bullets for many year in Australia. There is no doubt that without Gary’s mentoring skills, experience, industry contacts, generosity and patient personality, I would not have made any progress up the steep learning curve that is swaging bullets by hand.