Mark Heinen

Today we're gonna learn about ballistic coefficient and its measurement models. In plain english, a ballistic coefficient is a single number that tells you how well a bullet can/will cut through the air. A higher BC means the bullet loses speed slower, so it drops less, will drift in the wind less, and will retain more energy along its path. Two things drive ballistic coefficient: - Shape: long and pointy bullets will have higher BC's than flat, short chodey bullets - Weight for diameter (sectional density): heavy fat longboi's of a given caliber will fly better than chodes of the same caliber. There are multiple models for measuring BC, all using a "reference bullet" that was measured a long time ago. The two most common are: - G1: Basically wild-west bullets. Flat-nosed (even round-nosed) bullets dating back to the 1800's. Poor measurement for most modern match bullets. - G7: Long, sleek, sexy bullets with nice curves. This is the (mostly) best modern measurement until we get into radar-proven stuff. - Other models: G2, G5, G6, and G8: Less-common but for specific shapes. Rarely used. Newest Measurement Type: Radar - CDM/4DOF: Custom drag curves that measure a bullets actual drag (using radar flight data rather than shape and sectional density) to be as accurate in measuring it's projected path as possible. @TeamHornady "4DOF" and @AppliBallistics are leading the pack here. I mostly use these. Anyway. I'd like to let you know that the highest known G1 BC for .22LR is Lapua's 40gr lead round-nose match bullet. It's a G1 of 0.172 and no published G7 and flies around 1,100fps. Actually elite for .22 LR. An average 5.56x45 M193 55gr cheapo bullet has an approximate G1 BC of 0.243. It will fly (should fly) somewhere around 3,000fps (+/-). Not great to use G1 to measure this bullet, but it's an easy mental comparison. Standard 55gr FMJ for your AR. A quarter at 300 yards is a roughly .3 MOA group. Neither of these bullets are mathematically, or realistically capable of printing this pattern at 300 yards, no matter how good the shooter is. It's functionally impossible. Have a great day I'm going on a road trip today.