TargetTalk

Hello fellow shooters!

A friend of mine decided to try out a bloop tube for his Anschutz 1907. He choose a "Precise"-tube, I think is made by Anschutz themselves.

When he mounted the tube and tried a few shoots it first hit way to low, about 40cm to low. He mounted the foresight riser he had used on the original setup, (removed because the tubes mount is higher than the original mount) and tried again. This time he hit way to high!

Is there any good technique/method to measure or set this up?

I have the Precise Tube mounted on my old 1907.

For proper sight alignment with the foresight when mounted on the tube, the rear sight needs to be mounted on a 4mm sight riser. The Precise tube is not sold with it, of course. It must be purchased separately.

The design of the precise tube is such that it is the same diameter for the whole length of the tube, rather than stepping down to a smaller diameter towards the front end. So the foresight will be raised regardless of where it is mounted on the tube.

If you use any sight riser blocks an additional 4mm is still needed on the rear. So if you use a 8mm raiser for the front, the rear needs an 8mm and an additional 4mm (12mm total) to be aligned properly.

Hope that helps.

JV

Sammep wrote:Hello fellow shooters!

A friend of mine decided to try out a bloop tube for his Anschutz 1907. He choose a "Precise"-tube, I think is made by Anschutz themselves.

When he mounted the tube and tried a few shoots it first hit way to low, about 40cm to low. He mounted the foresight riser he had used on the original setup, (removed because the tubes mount is higher than the original mount) and tried again. This time he hit way to high!

Is there any good technique/method to measure or set this up?

Yes there is a formula to measure the sight radius, but I don't remember it or have it saved on this computer. I'm assuming 690cm barrel length and about a 6inch bloop tube? On my 1813 with a ESP tube I had to go 4cm shorter riser in front. Usually there is about 3-4 mm of difference in sight risers, front one is shorter than the back. Now also remember that front site heights are opposite than the back. Ex. If you have the front sight on a shorter riser the point of impact will go up, if you have a taller riser on the front than the back , the point of impact will go down. Somebody will chime in with the formula. Maybe?


Hope this helps,
Scott


Edited to add: Shootswithstyle beat me to the punch!

A bit of geometry from my schooldays:

Similar Triangles - IF your sightbase is 100cm and your target is 50m away then if you raise the foresight by 4mm the change in point of aim at the target will be 4mm x 50m/1m = 200mm. (Lower)

If your sightbase is 80cm then it would be 4mm x 50m/0.8m = 250mm and so on...

I don't quite understand how he could put a raiser under the foresight and then have the shots hit HIGHER...???
As ShootWithStyle says, a 4mm raiser under the REARSIGHT is generally a good starting place when using a tube.

K.