Grains and Ballistic Coefficient: Choosing a Bullet Weight in 6mm and 6.5
A heavier bullet is not always a better one. Weight, shape and twist rate decide what a small-bore rifle can do.
Bullet weight is stated in grains, and 7,000 of them make a pound. In the small bores, weight matters less than shape, because a long, pointed bullet holds its speed. That quality is summed up in a number called ballistic coefficient: the higher it is, the better the bullet resists air drag.
Light bullets: varmints and benchrestHornady's ELD-VT bullet, built for varmint and tournament shooting, sits at the light end of the 6mm ARC range, and the ELD-VT loads are at 6mm arc eld-vt ammo.
The 6mm BR is a benchrest cartridge whose loads often use lightweight bullets. HSM is one of the loaders that lists it, at hsm 6mm br ammo.
The middle: 100 to 120 grainsMost 6mm match cartridges use bullets of roughly 100 to 110 grains. The 6mm GT, at 6mm gt ammo for sale, lives in that range. So does the 6mm XC, at 6mm xc ammo.
The 6.5-284 Norma, at 6.5-284 norma 120 grain ammo, is loaded with 120-grain bullets among others, a weight that suits its long-range target role.
The 6.5 Creedmoor's match loads typically run 120 to 140 grains, and hollow-point match bullets, such as those at 6.5 creedmoor hollow point ammo, are a common choice there.
Heavier bullets: wind and rangeThe 6.5 PRC and the Weatherby 6.5-300 are built for heavier 6.5 millimeter bullets in the 140 to 156 grain class. Winchester's 6.5 PRC loads are at winchester 6.5 prc ammo. The 6.5-300 Weatherby Magnum, a 6.5 millimeter bullet on the belted .300 Weatherby case, is at 6.5-300 weatherby magnum ammo.
The 6.5x54 Mannlicher shows the older way: a 156-grain bullet at modest speed, as at 6.5x54 mannlicher 156 grain ammo. The 6.5 Grendel sits between the two, and anyone who wants to buy 6.5 grendel ammo will find that 120 to 130 grains is the norm.
Twist rate decidesWhatever the weight, the barrel has to spin the bullet fast enough to keep it stable. Longer, heavier bullets need a faster twist, so check your rifle's twist rate against the bullet weight before you buy a box.
Bullet weights and ballistics vary by maker and lot. Check the rifle's twist rate before choosing heavier bullets, and confirm current stock and state shipping restrictions before ordering.
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