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flatlander · July 1, 1999, 10:03 AM

Several years ago, some of us tried to use the Sierra 168gr.MK's in our M1A's at 100 yds. We found that, because of the shape of the bullet, and our rifles' chambers, the bullet wouldn't settle down, or "go to sleep" at 100yds. It was still a little wobbly and didn't group well until out to at least 200yds. Now moly coating is supposed to let the bullet slip a little and align itself better with the bore, so that as it exits the muzzle, there's not so much yaw or wobble to damp out. This lets the bullet "go to sleep" sooner, and results in better retained velocity, or in effect, higher effective BC. This is all pretty much theory, but it does explain the demonstrated higher BC's some experimenters have been getting with moly bullets, using two chronographs, one at the muzzle, the other downrange. The actual BC can be computed using the two velocity readings, and it's quite common for the actual or "realtime" BC to change along with atmospheric conditions.

[This message has been edited by flatlander (edited July 01, 1999).]

July 1, 1999, 10:03 AM	#9
flatlander Senior Member Join Date: June 16, 1999 Posts: 120	Several years ago, some of us tried to use the Sierra 168gr.MK's in our M1A's at 100 yds. We found that, because of the shape of the bullet, and our rifles' chambers, the bullet wouldn't settle down, or "go to sleep" at 100yds. It was still a little wobbly and didn't group well until out to at least 200yds. Now moly coating is supposed to let the bullet slip a little and align itself better with the bore, so that as it exits the muzzle, there's not so much yaw or wobble to damp out. This lets the bullet "go to sleep" sooner, and results in better retained velocity, or in effect, higher effective BC. This is all pretty much theory, but it does explain the demonstrated higher BC's some experimenters have been getting with moly bullets, using two chronographs, one at the muzzle, the other downrange. The actual BC can be computed using the two velocity readings, and it's quite common for the actual or "realtime" BC to change along with atmospheric conditions. [This message has been edited by flatlander (edited July 01, 1999).]