[GBullet]

Every year the wise and ethical hunters head to the range to confirm that their scoped rifles or slug guns are properly sighted-in. Mysteriously, some of the scoped guns are no longer sighted-in. This sends legions of hunters scratching their heads as to how this could be. After all, they reason, it was sighted-in when they shot it last season.

To the outside world riflescopes appear as a metal tube with a glass lens at each end. Unseen are several lenses and a second metal tube hidden within the first. This hidden, inner tube is the erector tube and it lies in the rear half of the scope. The forward end of the erector tube is held by the scope's elevation and windage adjustments and an elastic part.

When the rifle, or slug gun, is fired the erector tube is microscopically tossed to and fro. When the scope stops vibrating, the erector tube may have been displaced a small amount. Heavier, brass erector tubes are more likely to suffer this malady than light, aluminum tubes. Allowing the scope to suffer bumps and impacts prior to use can do the same thing. Unfortunately in scopes, even microscopic movement can have big consequences. We know this microscopic movement as "reticle shift".

And as Paul Harvey would say, "Now you know...the rest of the story."

 

[Rich Z]

I would think this would be of HUGE concern to benchrest target shooters. I mean with all the care going into the rifle and ammunition to get the tightest groups possible, doesn't this quirk of scopes negate at least some of that? What do they do about this problem? Certainly they don't just ignore it?

 

[brass hammer]

AND i would think?

that a heavier tube [brass] compared to alum. would be exacatly opposite


[hell, i'm half lunk headed mule]


i hope you talk about barrel harmonincs in a sporter weight varmint rifle,soon!

[this could be fun!]



thanks.

 

[RIKA]

The secret life of riflescopes

Awww gee, I thought you were going to explain why my old Leupold has a fetish for bikini lens covers.

RIKA

 

[GBullet]

I would think this would be of HUGE concern to benchrest target shooters. I mean with all the care going into the rifle and ammunition to get the tightest groups possible, doesn't this quirk of scopes negate at least some of that? What do they do about this problem? Certainly they don't just ignore it?

It has always been a concern for the benchrest folks. On page 113 of Warren Page's classic book The Accurate Rifle (1973) he talks about a new internally adjustable scope that may limit reticle shift enough to work for benchrest shooting!

Keeping reticle shift to a minimum is one of the reasons that Leupolds are popular for that sport. Among the most resistant of all scopes to reticle shift are the old East German Zeiss that used the wedge that was tapped into place. I know someone who has taken three dozen deer in the last 31 years using this scope and it is still sighted-in.

I bought my old deer rifle used. It came with a Weaver KV scope that had been made in 1949. It had been bumped around for years before I got it, yet it was perfectly on target when I first fired it.

 

[GBullet]

AND i would think? that a heavier tube [brass] compared to alum. would be exacatly opposite

A brass erector tube would be about 3 1/2 times as heavy as an aluminum tube. Picture yourself in an earthquake trying to keep a bookcase from falling over. It would be a lot easier if it were an aluminum bookcase than if it were a brass bookcase.

i hope you talk about barrel harmonincs in a sporter weight varmint rifle,soon!

I sure will.

 

[brass hammer]

thanks G-BULLET

i think YOU do know your stuff!



i can easily grasp the concept of a heavy/light book self in an earthquake!



but I can't help, but to hang on to the FACT that mass x resononics[?]i.e brass/alum.

flys in the face of sound conventional thinking.


thanks.

 

[Magnum88C]

The secret life of riflescopes

Awww gee, I thought you were going to explain why my old Leupold has a fetish for bikini lens covers.

RIKA

But. . .that's no secret! :dgrin:

 

[BigJon]

There's another reason too - some folks don't realize that many rifles will not shoot to the same point of aim in all conditions, even at only 100 yards. In a practical setting, zero tends to sort of "float" around the bull. One can fairly accurately determine where the initial shot will hit, though, through practice. By "practical setting", I am referring to field shooting (sans bench).

For this reason, one should not take one shot, and adjust, take another and adjust again, etc. One should shoot a group, and then adjust for the group. Also, one should not adjust for both windage and elevation at the same time - adjust for one, see where your group moves relative to the bull, and then adjust for the other if necessary.

Regards,
Jon