Figure 4: Litz BCs and Sierra’s claims for the Sierra GameKing bullets tested by Litz.
calculator was used from JBM. JBM is a free online provider for ballistics calculators. To determine the ballistic coefficient, the trajectory predicted with a given muzzle velocity (feet per second) needed to be calculated first. In determining the velocity at 200 yards the atmospheric conditions of altitude (ft.), humidity (%), temperature (F), and pressure (in Hg) are constants. The constants used for every bullet for ev- ery manufacturing company were 0 ft. altitude, 0% humidity, 59 °F, and 29.92 in Hg. With these constants the velocity of the bullet was calculated using the JBM calculator. With a muzzle velocity of 2800 fps and the calculated velocity at 200 yards was then used with the same atmospheric conditions to determine the G1 and G7 BCs. This process was repeated for all the Litz measurements reported here. For example, the BC for Hornady
.284 caliber Interlock SP 139 grain was determined in this manner. The bullet was looked up in the JBM trajectory (ve- locity) database under Litz’s bullets and then its trajectory was calculated using the atmospheric conditions mentioned above. For a muzzle velocity of 2800 fps, the velocity at 200 yards is 2530.4 fps. A near velocity of 2800 fps and a far velocity of 2530.4 fps at 200 yards was then used to compute the G1 bal- listic coefficient, which is 0.399, and G7 ballistic coefficient, which is 0.196. The atmospheric conditions for this calcu- lator also were the same conditions as when the trajectory was compared. Results
The results show the differences
in ballistic coefficients between the Litz measurements and the Barnes’ claims.
Figure 5: Litz and Sierra BCs for the Sierra MatchKing.
Style Diameter Mass SD (in)
(gr)
GameKing GameKing GameKing GameKing GameKing GameKing GameKing
Sierra Litz Litz Overestimate
0.277 150 0.284 150 0.284 175 0.308 165 0.308 180 0.308 200 0.338 250
(lbs/in²) G1 BC G1 BC G7 BC (%) 0.279
0.236 0.310 0.258 0.271 0.301 0.313
0.483 0.507 0.253 -4.73 0.436 0.441 0.220 -1.13 0.533 0.594 0.296 -10.27 0.404 0.426 0.213 -5.16 0.501 0.485 0.242 3.30 0.560 0.582 0.290 -3.78 0.565 0.533 0.266 6.00
Table 4: Litz BCs and Sierra’s claims for the Sierra GameKing.
Style Diameter Mass SD (in)
MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing MatchKing
Palma 0.308 Sierra Litz Litz Overestimate
(gr) (obs/in²) G1 BC G1 BC G7 BC (%) 0.224 52
0.224 69 0.224 77 0.224 80 0.224 90 0.243 70 0.243 95 0.243 107 0.257 100 0.264 107 0.264 123 0.264 142 0.277 115 0.277 135 0.284 168 0.284 175 0.308 168 0.308 175 0.308 180 0.308 190 0.308 200 0.308 210 0.308 220 0.308 240 0.338 250 0.338 300
0.148 0.196 0.219 0.228 0.256 0.169 0.230 0.259 0.216 0.219 0.252 0.291 0.214 0.251 0.298 0.310 0.253 0.264 0.271 0.286 0.301 0.316 0.331 0.361 0.313 0.375
155 0.233 0.504
0.225 0.223 0.112 0.90 0.301 0.338 0.169 -10.95 0.362 0.380 0.190 -4.74 0.420 0.435 0.217 -3.45 0.504 0.514 0.256 -1.95 0.259 0.263 0.132 -1.52 0.480 0.465 0.232 3.23 0.527 0.525 0.262 0.38 0.386 0.368 0.184 4.89 0.420 0.461 0.230 -8.89 0.510 0.522 0.26 -2.30 0.595 0.604 0.301 -1.49 0.324 0.323 0.162 0.31 0.488 0.507 0.253 -3.75 0.488 0.580 0.289 -15.86 0.608 0.657 0.327 -7.46 0.462 0.437 0.218 5.72 0.505 0.488 0.243 3.48 0.475 0.495 0.247 -4.04 0.533 0.542 0.270 -1.66 0.565 0.572 0.285 -1.22 0.645 0.635 0.316 1.57 0.629 0.623 0.310 0.96 0.711 0.667 0.332 6.60 0.587 0.630 0.314 -6.83 0.768 0.766 0.381 0.26 0.428 0.214 17.78
Table 5: Litz BCs and Sierra’s claims for the Sierra MatchKing bullets tested by Litz.
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