TODAY'S TUNNEL REPORT, Barrel Indexing

G

Gene Beggs

Active member
It was quite cool at the tunnel this morning. I did not notice the actual temperature but I would guess it was about twenty degrees cooler than the evening before.

Before shooting, the barrel was rotated a quarter turn to the right from where the shooter sits. As I stated in another post, the group the evening before was estimated conservatively at .125. Using the same ammunition loaded the day before, the barrel was fired a couple of times to foul the bore; it showed two bullet holes of vertical and the tuner was rotated a half turn out. The next two shots showed no vertical so I went to the record.

The group fired after the barrel was re-indexed a quarter turn to the right was indistinguishable from one bullet hole! :D You be the judge.

Tomorrow, I will rotate the barrel another quarter turn to the right and we will see if that changes anything. I marked the barrel carefully after shooting it this afternoon because I don't see how you could improve on that.

Some question the effectiveness of barrel indexing but I know otherwise. I KNOW it works and works well. It can often change a bummer into a hummer. Don't believe it? The only thing I can say is, "Let me show you." :)

Something that should be remembered is the fact that the adjustable bushing indexing system does not change the barrel length one iota. If you add shims, change bolts, or any other action that changes the barrel length in some way, you do not actually have the same barrel and any tests performed in this manner would be invalid.

Later,

Gene Beggs
 
Gene, some interesting feedback would be to note if the POI follows the indexing and by how much does the POI shift.
 
JerrySharrett said:
Gene, some interesting feedback would be to note if the POI follows the indexing and by how much does the POI shift.
Click to expand...


Thank you Jerry, good point and I forgot to mention that yesterday.

The first group printed at about 1:00 o'clock on the ten ring. After the barrel was re-indexed a quarter turn clockwise, the group printed at 12:00 on the nine ring.

Gene Beggs
 
thanks for the answer

the only difference you may find is that with rimfires the lowest POimpact on the clock arotation or indexing is usually the best and with centerfires, Gene will tell us.

not wanting to say others are wrong but wait and see, Gene is on the right track

Jefferson
 
Gene Beggs said:
Thank you Jerry, good point and I forgot to mention that yesterday.

The first group printed at about 1:00 o'clock on the ten ring. After the barrel was re-indexed a quarter turn clockwise, the group printed at 12:00 on the nine ring.

Gene Beggs
Click to expand...


Wow! That seems to defy all other barrel indexing POI results that I have seen published by the likes of Brian Harvey, Mike Ross, Calfee, and myself.

Usually, if a barrel is index clocked in a clockwise rotation, the POI will follow the same clockwise pattern, and not reverse in its rotation/POI pattern as it has for Gene.

The only exception that I have seen before to this rule, is a railgun barrel that I index clocked in a clockwise manner and the 3 and 9 oclock POI were at the same spot while the 12 and 6 oclock POI were 1 inch apart above/below the 3-9 orientations.

Wonder if this has something to do with Genes differential insert acting in an otherwise not understood manner?

Of course, Gene probably has alot more shooting and testing to do before coming to some hard and true conclusions, this may be an annomoly and will all come out in the wash with further testing..................Don

PS.........having thought more about Genes results, it could be that Genes clockwise rotational pattern is holding true-to-fashion, and his first index orientation will turn out to be the lowest 6 oclock position (which explains why it shot so well, at least according to Mike Ross's theory), and the second index position will be the 9 oclock orientation, thereby explaining why the second POI was higher and to the left. If this follows true-to-fashion, the next index POI should be even higher and to the right thereby indicating the 12 oclock barrel orientation position.

Wonder if Gene could look down the barrel bore while it is spun in his lathe to see if the POI orientation matches the visual curvature of the barrel, if it is pronounced enough and in a simple or semi uni-curved direction?
 
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Gene Beggs said:
Some question the effectiveness of barrel indexing but I know otherwise. I KNOW it works and works well. It can often change a bummer into a hummer. Don't believe it? The only thing I can say is, "Let me show you." :)
Click to expand...
Click to expand...

Gene, I've been watching your indexing threads since you started posting your findings....very interesting stuff, to say the least. I don't question the validity of your findings, because it all makes sense, and I haven't seen any evedence to the contrary.

Your statement that indexing "can often change a bummer to a hummer" does leave me with a few questions, though. Are you testing outdoors in addition to in your tunnel? If not, how do you determine that a barrel is a hummer in static conditions?

-Dave-:)
 
Dave, I do all my testing in the tunnel. In the Beggs cartridges, both the 220 and 6mm, I shoot in the upper load window so I'm not shooting squib loads. I believe if a barrel will shoot in the tunnel, it will also shoot outside. I guess I should quit using the term 'hummer' because everyone has their own idea what that means.

Later,

Gene Beggs
 
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