The Firing Line Forums - View Single Post - Higher Velocity Can Mean Greater Field Accuracy

Bart B. · July 9, 2013, 08:55 AM

Food for thought; i.e. facts for reasoning in these issues.....

All firearms move a bit such that their bore axis points to a different place when the bullet exits compared to where it pointed when the primer fired the round. Some examples:

* Double rifles' barrels toe in at the muzzle. Typically, the bore axis crosses at 10 to 25 yards depending on the recoil. The distance between the muzzle axes is less than the distance between the breech axes. They're "regulated" by moving a wedge between the barrels to zero at 50 or 100 yards. The front sight height on a .500 NE Rigby double I measured was higher above the bore than the rear sight's leaves; proof to me the bore axes rise a bit while the bullets go down the barrel. After all, the recoil axis is above the shooter's shoulder where the stock's butt plate is.

* Handgun front sights' top is higher than their rear sight's tops; go measure them yourself. The bore axis points below the aiming point when the firing pin smacks the primer.

* .22 rimfire free pistols were designed decades ago such that their bore axis aligned with the shooter's arm axis minimizing muzzle axis jump during the time bullets went down the barrel.

* Several people shooting the same rifle with a given load will each have their own zeros on the sights for a given range. This is because each person holds the rifle slightly different and its recoil amout and direction varies a bit while the bullet's going down the barrel. I have observed this with both bolt guns and semiautos with scope and aperture sights "hot gunning" the same rifle and ammo in long range team matches. There's easily a 1 MOA difference. It ain't because they each look through the sights differently; an other decades-old myth.

Regarding high velocity, if a 22 caliber bullet at high velocity is so much better than a 30 caliber one at a medium velocity as far as accuracy is concerned, then why did the US Army get the NRA to allow AR10's in .308 Win. to be classified as a service rifle and finally equip them to shoot scores equal to what 7.62 NATO chambered service rifles, (M1, M1A) did out scoring those using 5.56 NATO rounds? The best 5.56 NATO rifles could not out shoot the best 7.62 NATO ones as far as hitting the target's highest-scoring rings at ranges greater than 600 yards.

It's too darned hard to get low muzzle velocity spreads with higher muzzle velocities in any caliber. Which is why such cartridges are not popular, successful nor desired by folks knowing what's best to score and group well.

July 9, 2013, 08:55 AM	#12
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Food for thought; i.e. facts for reasoning in these issues..... All firearms move a bit such that their bore axis points to a different place when the bullet exits compared to where it pointed when the primer fired the round. Some examples: * Double rifles' barrels toe in at the muzzle. Typically, the bore axis crosses at 10 to 25 yards depending on the recoil. The distance between the muzzle axes is less than the distance between the breech axes. They're "regulated" by moving a wedge between the barrels to zero at 50 or 100 yards. The front sight height on a .500 NE Rigby double I measured was higher above the bore than the rear sight's leaves; proof to me the bore axes rise a bit while the bullets go down the barrel. After all, the recoil axis is above the shooter's shoulder where the stock's butt plate is. * Handgun front sights' top is higher than their rear sight's tops; go measure them yourself. The bore axis points below the aiming point when the firing pin smacks the primer. * .22 rimfire free pistols were designed decades ago such that their bore axis aligned with the shooter's arm axis minimizing muzzle axis jump during the time bullets went down the barrel. * Several people shooting the same rifle with a given load will each have their own zeros on the sights for a given range. This is because each person holds the rifle slightly different and its recoil amout and direction varies a bit while the bullet's going down the barrel. I have observed this with both bolt guns and semiautos with scope and aperture sights "hot gunning" the same rifle and ammo in long range team matches. There's easily a 1 MOA difference. It ain't because they each look through the sights differently; an other decades-old myth. Regarding high velocity, if a 22 caliber bullet at high velocity is so much better than a 30 caliber one at a medium velocity as far as accuracy is concerned, then why did the US Army get the NRA to allow AR10's in .308 Win. to be classified as a service rifle and finally equip them to shoot scores equal to what 7.62 NATO chambered service rifles, (M1, M1A) did out scoring those using 5.56 NATO rounds? The best 5.56 NATO rifles could not out shoot the best 7.62 NATO ones as far as hitting the target's highest-scoring rings at ranges greater than 600 yards. It's too darned hard to get low muzzle velocity spreads with higher muzzle velocities in any caliber. Which is why such cartridges are not popular, successful nor desired by folks knowing what's best to score and group well. Last edited by Bart B.; July 9, 2013 at 10:51 AM.