Bright Focus

Sight Apertures

 The Bright image of a large aperture and the sharp Focus of a small aperture,

at the same time … Bright Focus!

 

Installation on a Bob Jones sight

IMPORTANT. 

  1. Before installing this sight, or doing any work on a rifle, always check to make sure it is unloaded, the magazine is out, and the bolt is locked open.
  2. Do not attempt to make any modifications to your weapon if you are not competent, and comfortable with the task.  If you are unsure, take the weapon to a qualified gunsmith.

 

INCLUDED IN KIT

            Sight aperture, 12-15 shim washers of 0.001” each.

 

SIZE EQUIVALENTS

            BRIGHT FOCUS sight apertures are marked with a size.  The marked size is the equivalent diameter (in thousandths) of a round sight aperture with the same total open area, and should give the same image brightness to the shooter.

 

ORIENTED FOCUS SIZE

ROUND APERTURE SIZE OF EQUIVALENT BRIGHTNESS

ACTUAL SIZE OF ORIENTED FOCUS APERTURE

36

0.036”

0.023” x 0.045”

38

0.038”

0.024” x 0.048”

40

0.040”

0.025” x 0.050”

42

0.042”

0.026” x 0.052”

48

0.048”

0.030” x 0.060”

54

0.054”

0.033” x 0.067”

 

Bob Jones Sizes: #1 = 0.042”; #2 = 0.046”; #3 = 0.051”; #4 = 0.055”

 

INSTALLATION

If you have a Bob Jones rear sight, the Oriented Focus sight aperture is a direct replacement for a Bob Jones aperture.  The only difference is that the sight needs to be installed such that the rectangular opening ends up oriented horizontally when the aperture is tightened.  In this orientation, the ‘flat’ of the hexagonal outer shape should be on the top when tightened.  Shim washers are included in order to make this adjustment.  Follow these steps to install your sight aperture:  

  1. Remove the Bob Jones aperture from your rear sight.  The BRIGHT FOCUS apertures will screw on to the threaded tube of the Bob Jones hood in place of the Bob Jones apertures.  The only difference is that shim washers will be needed between the sight leaf and the aperture to get the rectangular opening to be horizontal after assembly is complete.      Note: disassembly of your rear sight is NOT necessary.  Photos shown are disassembled only for clarity of the instructions.

  2. Screw on the BRIGHT FOCUS sight aperture finger tight until the skirt of the aperture seats against the flip sight leaf.

  3. Observe the orientation of the rectangular aperture by imagining a line drawn across the widest dimension of the rectangle as if it were the hour hand of a clock.  In Figure 1, below, the rectangle points to 2 o’clock and 8 o’clock .

  4. In order to be oriented correctly, the aperture needs to be unscrewed by the equivalent of 5 hours (150 degrees) to get the imaginary line pointed horizontally at 3 o’clock and 9 o’clock .  This adjustment is made by adding 2 washers per ‘hour’ of loosening required between the aperture and the sight leaf.  (Note, you cannot overtighten the aperture to adjust the extra hours forward, or you risk damaging it).  In this case, the 5 hour adjustment requires you to add 10 washers.

  5. Reinstall the aperture with the shim washers and snug into place.  The final aperture orientation will be horizontal (Fig. 2).  If necessary, try with one more or one less washer to get the aperture as close to horizontal as possible.  It is NOT critical that the rectangular opening be perfectly horizontal.  A tilt of 5 or 10 degrees will not diminish the focus benefit of this aperture.

 

NOTE:  When looking through your sight from up close, you will probably not notice that it is rectangular.  Hold your head back 18” to properly judge the sight orientation.

 

NOTE: The size markings on your aperture might not end up being oriented right side up.  If the numbers are upside down, this is also a correct orientation.