The heaviest 7mm and .30 cal bullets have practically the same BC, which means that given equal muzzle velocities, both will be deflected an equal amount in a given crosswind.
However, consider the statement: “assuming equal muzzle velocities…” Even a moderate 7mm chambering is capable of delivering 2800 to 3000 fps with the heavy 7mm bullets, much faster with magnums. The heaviest .30 cal bullet requires a big magnum just to get to 2800 fps. So the first problem is: you can’t get the heavy .30 cal bullets going as fast as the heavy 7mm bullets! Even if you could get the same muzzle velocities from the heavy .30 cal bullets, it would take much more powder to do it, barrel life would suffer, and you’ve only achieved parity with the 7mm. The various negative effects of the incredible recoil are really just the "nail in the coffin" for the heavy .30 caliber bullets. If the available heavy .30 caliber bullets had lower drag profiles, they would have higher BC’s, and wouldn’t require equal muzzle velocities. Remember, when loaded to the same pressure, a bullet with a higher BC will have less wind deflection even though it starts at a lower muzzle velocity. But the truth of the currently available heavy .30 caliber bullets is; they don’t have higher BC’s than the heavy bullets in smaller calibers.
To answer the question posed by the title: What’s Wrong With .30 caliber? I offer the following explanations:
• Lack of legitimate “heavyweight” (~230 grain class) .30 caliber bullets.
• The bullets that are in the “heavyweight” class for .30 caliber have higher drag profiles than the heavy bullets in smaller calibers.
• Most .30 caliber long range shooters use 190 – 210 grain bullets, thinking that’s “heavy enough”, when that’s actually a “middleweight” bullet for .30 caliber. These “middleweight” bullets, even from .30 cal magnums, will tend to suffer more wind deflection (if only slightly) when compared to the “heavyweight” 6.5mm and 7mm offerings.
• The energy (powder) required to propel a truly “heavy” .30 caliber bullet to reasonable speeds produces recoil that’s considered prohibitive for most applications, except maybe unlimited class benchrest where rifles have no weight restriction.
Many people do very well with .30 caliber rifles at long range. I have to ask: are they doing well because of the caliber, or in spite of it?
I would like to thank German Salazar for his contributions to this article. In particular, the resources and advice provided on the historical perspective of .30 caliber match bullet development are critical to the understanding of this caliber today. Furthermore, an explanation of the recoil effects by someone who’s shot a lot of 240 grain .30 cal bullets downrange was a valuable contribution.
[Ref1] Bryan Litz, “Understanding Long Range Bullets Part 1: The Nature of Scale” Precision Shooting, May 2007.
[Ref2] Geoffrey Kolbe, “Comments on Long Range Ballistics” NRA Journal, Spring 1996.
[Ref3] German Salazar, “A Long Range Shooter Looks at Heavy Bullets” www.6mmbr.com
[Ref4] Bryan Litz, “Ballistic Coefficient Testing of the Berger .308 155 Grain VLD” Precision Shooting, March 2008.
[Ref5] Dr. K. C. Erikson, “The Evolution of the Match Bullet” Precision Shooting Special 3 Vol. 1, 1995.
Bryan Litz majored in Aerospace Engineering at Penn State University and worked on air-to-air missile design for 6 years in the US Air Force before taking a job as Berger Bullets Chief Ballistician in November 2008. Bryan is now 29 years old, and has been an avid long range shooter since the age of 15. In particular, Bryan enjoys NRA Long Range Prone Fullbore/Palma competition and is the current National Palma Champion. Bryan is also a husband, and proud father of 3.
Precision Shooting magazine is one of the oldest continuously published firearms magazines in the US; its first issue was in May of 1956. While it if often thought of as "home" by Benchrest shooters as well as Highpower and Smallbore shooters, its subscription base is considerably broader. Other areas that are given frequent coverage include wildcat cartridges, military sniping, long range varmint shooting, accuracy gunsmithing and reloading, equipment reviews and firearms-related history. Its cadre of writers is unique and most of them write only for this publication.
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