Dan Newberry's Optimal Charge Weight Load Development go to ocwreloading.com

green 788

Note: The acronym OCW and the phrase "Optimal Charge Weight" as related to the reloading of metallic cartridges are terms originated by the author of this site. When referencing OCW or Optimal Charge Weight in your personal documents, please add a link to this website for clarification purposes.

Tools, page 3


A brief preface: Remember that we're discussing the 1/2 MOA rifle here. Keep in mind that a good batch of Federal Gold Medal Match ammo will maintain 1/2 MOA groups from a well put
together rifle. This factory ammo does this without the benefit of deburred flash holes, squared primer pockets, meticulously seated bullets, et al.
Expensive sizing and seating dies.  With the commonly available dies, provided you're using them correctly, you will be able to assemble ammo which is more accurate than your 1/2 MOA rifle likely is. Fancy and expensive seating dies will rarely improve your groups--provided you're using a good load recipe to begin with. The other tolerances in the entire chain of variables will probably eclipse any presumed benefit from a precision loading die. The standard RCBS dies and the Lee dies (especially the Lee Collet neck sizing dies) are more than adequate for the 1/2 MOA rifle.
Case neck turning devices.  When brass cases are made, they are rarely perfect. The case neck may be a bit thicker on one side than the other. This condition will often cause the bullet to seat crooked in the case, and a crooked bullet (excess runout, remember?) can cause the shot to go outside the group. The thing is, though, that for the 1/2 MOA rifle you're not likely to benefit one
iota from doing this. These tools can cost as much as sixty dollars for some models, perhaps more for others. However, it has been noted (even by the advocates of neck turning) that unless there is more than .002" (two thousandths of an inch) of disparity in the neck wall thickness, the case needn't be corrected. And what about the cases which do have more than this amount of
neck thickness variation? Toss 'em in the trash, or use them for fouler shots. The quality control has to deteriorate to near rock bottom before a case will be this bad. It will likely have other QC issues in addition to the poor case neck symmetry. As an aside, you would measure the case neck thickness with specialty gauges, such as the RCBS Casemaster, NECO, or other such tools
made for the purpose. But don't be anal. You can get a well made rifle shooting 1/2 MOA groups by simply buying a decent batch of Winchester brass and properly developing the load. If you'd rather spend the extra money for Lapua brass, I won't argue with you there ;) ...
Chamber length gauging tools.  These devices are designed to allow you to find the magic "distance to the lands" of a particular bullet in your particular rifle. This practice is one of the most bizarre of them all. Remember the afformentioned Federal Gold Medal Match ammo? It doesn't enjoy the presumed benefit of being seated "X thousandths off the lands." So how does it shoot so doggone well? The truth is that the distance of the bullet to the lands doesn't really matter a whole lot--provided all cartridges are loaded to the same length. It's true that you don't want to seat the bullet too close to the lands with a maximum pressure load, as pressure does increase as we move toward the lands. You also don't want to seat the bullet too deep either. This uses up powder space and it will mean that the bullet will have to "jump" through mid air for a finite amount of time before engaging the rifling. If the bullet is seated crooked (excess runout) it will collide with the lands off center. The longer the jump, the faster the bullet will be moving when it collides off center. The damage to the bullet's integrity is directly proportional to the velocity at which it hits the riflings off center. This is one possibility why many folks note improved accuracy by seating closer to the lands, as doing so tends to negate (to a degree) the ill effects of runout. All this
said, the exact amount of distance to the lands is largely immaterial. Often the rifle's magazine length will dictate a maximum length far away from the lands. Find an accurate overall length of the cartridge and stay in that general zone. If a .005" change of cartridge length spoils your accuracy, move ten thousandths in the other direction (if possible) and test the accuracy of that COL. If it's acceptable, you'll likely be closer to the actual optimum length for the cartridge. How far am I from the lands? Who cares! :)

The above observations are, of course, my opinions. I do base these opinions on my own experiences as well as the acute observation and study of the experiences of others. If there is one certain thing about the craft of handloading, it's that everyone has his own method and madness. Again, I offer the above in the hopes that some folks heretofore not involved in the making of their
own ammuntion will seriously consider giving it a try. With an understanding that making accurate ammunition doesn't necessarily have to involve several hundred dollars worth of equipment (to include the seemingly obligatory battery of tangential accessories) I think more folks will be inclined to get involved in handloading thier own ammunition. And that's a good thing! :)
Dan Newberry

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