Hornady .243 caliber 105 grain Amax

Dimensions taken from Lot #208199

Sample Size:

5

Ogive Radius:

10.09

Sectional Density:

0.254 lb/in2

Rt/R:

0.88

  The 105 grain Hornady Amax is a very well designed bullet with good performance.  The plastic tip promotes a little higher and more consist BC compared to standard match bullet meplats while the 2.71 caliber long tangent ogive produces a low drag profile and good accuracy over a wide range of seating depths.  If there is improvement to be made on this design it's probably in the boat tail length.  At only .135" (.56 calibers) this boat tail could be more effective at reducing base drag if it were a touch longer.

  According to the Miller Stability formula, this bullet exhibits adequate stability from a 1:8" twist in most scenarios, and marginal stability in the worst case scenario.  

  The experimentally determined average G1 BC of 0.492 varies from .515 at 3000 fps down to .454 at 1500 fps.  The G7 BC is a much better match for this bullet, as it only varies from .249 to .253 for an average of .252.

  Application-wise, this bullet was designed to be a match bullet, but has found favor with hunters as well due to the relatively thin forward jacket promoting good expansion.  From medium to large capacity 6mm cases, this bullet can produce excellent results to mid range (~600 yards) and can even reach to 1000 yards in some circumstances if driven hard enough, although performance at 1000 will not be as good as larger caliber, higher BC rounds.

Drag and Ballistic Coefficient

Fps/Mach

Cd

i7

G7 BC

i1

G1 BC

1500/1.34

0.369

1.006

0.253

0.559

0.454

2000/1.79

0.320

1.021

0.249

0.514

0.495

2500/2.23

0.286

1.007

0.252

0.506

0.502

3000/2.68

0.261

1.006

0.253

0.493

0.515

Average:

1.010

0.252

0.518

0.492

Variation:

0.015

0.004

0.066

0.061

Rifling Twist Rate and Stability

Stability Factor

Barrel Twist

Best case

Nominal

Worst Case

1:7”

2.21

1.93

1.67

1:8”

1.69

1.48

1.28

1:9”

1.34

1.17

1.01

1:10”

1.08

0.95

0.82

*Stability Factor above 1.4 indicates good stability.  Below 1.4 indicates marginal stability.  Less than 1.0 is unstable.