# Nose Cone Design or Projectile Ogive 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.

## Radius of an arc or segment

Given an arc or segment with known width and height:

The formula for the radius is:

 where: W  is the length of the chord defining the base of the arc H  is the height measured at the midpoint of the arc’s base.

# 7mm.com.au – Antipodean Industrial

Here is the link to an interview by Craig McGowan with me discussing Antipodean Industrial, G7<sub>L</sub> projectiles and bullet swaging.

# Gallery

Completed batch of G7L-264-140gr’s

# Calibres, Weights and Pack Sizes

Please confirm pricing at the time of order. Shipping not included, please confirm when ordering.

If you don’t see a particular weight listed in the calibres below, send an enquiry via email or the contact form.

 Calibre Mass(gr) Est. Mach Averaged BCG7(1) Min Twist per 100 per 500 Code 224 80(2) 0.216 1:8” \$50.00 \$241.56 G7L-224-80 243 105 0.242 1:8” \$70.00 \$338.17 G7L-243-105 257 135 1:8.5” NA NA NA 264 130 0.258 1:8” \$84.00 \$405.79 G7L-264-130 264 140 0.278 1:8” \$85.00 \$410.63 G7L-264-140 284 168 0.319 1:10” \$87.00 \$420.31 G7L-284-168 “The Norm” 284 175 1:9” \$88.00 \$425.12 G7L-284-175 284 180 0.342 1:9” \$88.00 \$425.12 G7L-284-180 308 150 1:14” \$61.00 \$294.69 G7L-308-150 308 155(3) 0.239 1:13 \$86.00 \$415.47 G7L-308-155 308 168 1:13” \$86.00 \$415.47 G7L-308-168 308 175 1:13” \$87.00 \$420.31 G7L-308-175 308 185 1:12” \$88.00 \$425.12 G7L-308-185 308 190 1:11” \$89.00 \$429.94 G7L-308-190 Calibre Mass(gr) Est. BCG7(1) Min Twist per 50 per 500 Code 308 210 0.334 1:11” \$46.00 \$444.50 G7L-308-210

Notes:

(1) Based on the “G7 form factor prediction” as described by Litz (2011, 573)

(2) Based on ICFRA Tech Rules & Regs for Fullbore TR 2008 Ed. 3 – Jul 2008 rule T2.19.2.1.

(3) Based on ICFRA Tech Rules & Regs for Fullbore TR 2008 Ed. 3 – Jul 2008 rule T2.19.2.2.

# Introducing the G7L series of projectiles

 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.

# FAQ

 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.