The Firing Line Forums - View Single Post - Why does decreasing the jump across the throat have an effect on accuracy?

Doyle · January 23, 2017, 05:10 PM

It all has to do with barrel harmonics. Your barrel is not a perfectly straight "pipe" during the firing. It actually moves like a snake - but in tiny, microscopic amounts. The more consistently you can get the bullet to exit the muzzle at the same "vibration" position, the better your gun will group. The amount of jump affects the pressure spikes (there are actually two pressure peaks if I recall) which in turn affects how that barrel is going to move as the bullet travels down it.

Now, some really knowledgeable folks are likely to come along and give you a proper scientific explanation.

January 23, 2017, 05:10 PM	#2
Doyle Senior Member Join Date: June 20, 2007 Location: Rainbow City, Alabama Posts: 7,167	It all has to do with barrel harmonics. Your barrel is not a perfectly straight "pipe" during the firing. It actually moves like a snake - but in tiny, microscopic amounts. The more consistently you can get the bullet to exit the muzzle at the same "vibration" position, the better your gun will group. The amount of jump affects the pressure spikes (there are actually two pressure peaks if I recall) which in turn affects how that barrel is going to move as the bullet travels down it. Now, some really knowledgeable folks are likely to come along and give you a proper scientific explanation.