The Firing Line Forums - View Single Post - 257 Roberts, 6.5x55 Swede, or 7x57 mauser

**Mike Irwin** · March 2, 2013, 12:01 PM

Whoops, made an error in the above...

I said Ballistic Coefficient... that's wrong.

I should have said Sectional Density. Sectional density is the critical factor once the bullet hits the target.

As an example...

Hornady makes a 160-gr. soft point round nose in 6.5mm that is close to the old 6.5x54 military round. Not the same, though, as the jacket is thinner and it's designed to expand.

It has a sectional density of .328.

A commonly used .308 caliber bullet is Hornady's 150-gr. Interlock boattail soft point. That bullet has a sectional density of .226, a HUGE difference between it and the 6.5 bullet.

March 2, 2013, 12:01 PM	#37
Mike Irwin Staff Join Date: April 13, 2000 Location: Northern Virginia Posts: 41,379	Whoops, made an error in the above... I said Ballistic Coefficient... that's wrong. I should have said Sectional Density. Sectional density is the critical factor once the bullet hits the target. As an example... Hornady makes a 160-gr. soft point round nose in 6.5mm that is close to the old 6.5x54 military round. Not the same, though, as the jacket is thinner and it's designed to expand. It has a sectional density of .328. A commonly used .308 caliber bullet is Hornady's 150-gr. Interlock boattail soft point. That bullet has a sectional density of .226, a HUGE difference between it and the 6.5 bullet. __________________ "The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower.