Gene Beggs
Active member
Those of you who have followed my previous posts know, I have experimented with barrel indexing for several years. Much progress has been made and after more than five years of brainstorming, trial and error, successes and failures, I have at last discovered a simple, inexpensive way to accomplish what for years, appeared to be impossible. 
More on this later.
Harold Vaughn's book, "Rifle Accuracy Facts" (RAF) was published in 1998 by Precision Shooting. It was edited by Dr. Jack Jackson. If you are serious about extreme rifle accuracy and do not have a copy of this book, I strongly urge you to obtain one as soon as possible. Chapter four, the section on barrel vibration alone, is worth its weight in gold.
In chapter 4, Vaughn begins by saying,
"Barrel vibration is one of the largest contributors to rifle inaccuracy; however, I have been unable to find any evidence of previous experimental work on the subject."
In his book, Vaughn goes into great detail about vibration experiments he conducted with a bolt action Remington chambered in 270 Winchester.
Most of what I know about barrel vibration and exterior ballistics, I owe to Harold Vaughn, and Dr. Jack Jackson. If not for these two gentlemen, I would have never figured out my barrel indexing system.
To make a long story short, rifle barrels whip up and down like a long, flexible fishing pole when fired as they hang out into space, suported only by the front receiver ring. Some refer to this as "barrel harmonics." Guys, I'm sorry but I still think the word 'harmonics' is far too complicated and mysterious sounding.
If the barrel is perfectly straight (very few are) the vibration is primarily in the vertical plane; the muzzle comes to a complete stop at the top and bottom of the swing. If we tune the rifle so the bullets exit at one or the other of the stops, there will be little or no vertical dispersion. But, have you ever seen a barrel that you could not tune? When you got the vertical out, the darn thing showed two bullet holes of horizontal and vice versa.
Such a barrel has a built in curvature and this curvature was unknowingly indexed in other than the vertical plane when chambered. The chances of this vibration frequency matching that of the vertical plane are slim. The muzzle of such a barrel is never stopped. If we re-index the barrel so the curvature is hidden in the vertical plane, the horizontal disappears.
In the past, the only way this situation could be corrected was to remove the barrel, turn a little off the tenon shoulder to allow the barrel to come to rest in the proper position, then remove the same amount from the breach and run the finish reamer in to obtain the correct headspace. This was time consuming and expensive. Most gunsmiths would run backwards at the mere mention of such.
Now, let's get down to the nitty gritty of this thing; how do we do it? This is mostly for you engineer and gunsmith types. The requirement is to be able to re-index the barrel to any clock position on the receiver without affecting headspace using only a barrel vise and action wrench, we want to be able to quickly and easily reindex the barrel at the range. Before I tell you how I did it, I want you to think about it and come up with the way you think it should be done. This is going to be interesting.
Later,
Gene Beggs
More on this later.Harold Vaughn's book, "Rifle Accuracy Facts" (RAF) was published in 1998 by Precision Shooting. It was edited by Dr. Jack Jackson. If you are serious about extreme rifle accuracy and do not have a copy of this book, I strongly urge you to obtain one as soon as possible. Chapter four, the section on barrel vibration alone, is worth its weight in gold.
In chapter 4, Vaughn begins by saying,
"Barrel vibration is one of the largest contributors to rifle inaccuracy; however, I have been unable to find any evidence of previous experimental work on the subject."
In his book, Vaughn goes into great detail about vibration experiments he conducted with a bolt action Remington chambered in 270 Winchester.
Most of what I know about barrel vibration and exterior ballistics, I owe to Harold Vaughn, and Dr. Jack Jackson. If not for these two gentlemen, I would have never figured out my barrel indexing system.
To make a long story short, rifle barrels whip up and down like a long, flexible fishing pole when fired as they hang out into space, suported only by the front receiver ring. Some refer to this as "barrel harmonics." Guys, I'm sorry but I still think the word 'harmonics' is far too complicated and mysterious sounding.
If the barrel is perfectly straight (very few are) the vibration is primarily in the vertical plane; the muzzle comes to a complete stop at the top and bottom of the swing. If we tune the rifle so the bullets exit at one or the other of the stops, there will be little or no vertical dispersion. But, have you ever seen a barrel that you could not tune?
When you got the vertical out, the darn thing showed two bullet holes of horizontal and vice versa. Such a barrel has a built in curvature and this curvature was unknowingly indexed in other than the vertical plane when chambered. The chances of this vibration frequency matching that of the vertical plane are slim. The muzzle of such a barrel is never stopped. If we re-index the barrel so the curvature is hidden in the vertical plane, the horizontal disappears.
In the past, the only way this situation could be corrected was to remove the barrel, turn a little off the tenon shoulder to allow the barrel to come to rest in the proper position, then remove the same amount from the breach and run the finish reamer in to obtain the correct headspace. This was time consuming and expensive. Most gunsmiths would run backwards at the mere mention of such.
Now, let's get down to the nitty gritty of this thing; how do we do it? This is mostly for you engineer and gunsmith types. The requirement is to be able to re-index the barrel to any clock position on the receiver without affecting headspace using only a barrel vise and action wrench, we want to be able to quickly and easily reindex the barrel at the range. Before I tell you how I did it, I want you to think about it and come up with the way you think it should be done. This is going to be interesting.
Later,
Gene Beggs
