Sierra .308 caliber 155 grain Palma

Sample Size:

5

Ogive Radius:

9.05  calibers

Sectional Density:

0.233 lb/in2

Rt/R:

0.94

 This bullet is a relatively new design to the Sierra line of MatchKing bullets.  Specifically designed for the US Palma team, this bullet first saw competition in the 2008 America Match: A bi-annual international FULLBORE match.  The US Team used the bullets to great effect by winning the match with most of the point spread being established at the longer ranges which is a testament to the ballistic performance of this bullet (and coaching).  What’s more impressive is that the 2008 America match was the first time most of the shooters had seen the bullet, which is a testament to how accurately this bullet shoots from a wide variety of rifles with very little load development.

    Since it’s introduction in 2008, this bullet has become the official Palma bullet of the US Rifle team.  It’s the bullet that the US Rifle Team will be using in the 2011 World Championships in Brisbane, Australia.

    Although very effective as a target bullet in a single shot rifle, this bullet has a long nose (necessary for good ballistic performance), and would not work well in a magazine fed scenario where the OAL of the loaded round is limited.

Drag and Ballistic Coefficient

Fps/Mach

Cd

i7

G7 BC

i1

G1 BC

1500/1.34

0.380

1.034

0.226

0.575

0.406

2000/1.79

0.324

1.033

0.226

0.520

0.449

2500/2.23

0.286

1.007

0.232

0.506

0.461

3000/2.68

0.259

0.996

0.234

0.488

0.478

Average:

1.018

0.229

0.522

0.449

Variation:

0.038

0.009

0.087

0.072

Rifling Twist Rate and Stability

Stability Factor

Barrel Twist

Best case

Nominal

Worst Case

1:10"

2.68

2.34

2.02

1:11"

2.21

1.93

1.67

1:12"

1.86

1.62

1.40

1:13"

1.58

1.38

1.20

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