How do I sight in a Duplex Reticile scope?

SOURCE: caps will not screw off

Many cap threads are reverse. try unscrewing the other direction. If this doesnt work my suggestion is to use physics to get it off.

Image a jar that is 1 litre with a lid that is 10 cm across. it takes x amount of force to unscrew that jar.
Now if that same jar has a lid that is 25 cm across there is a power advantage and a speed reduction.

Now to apply this to your thread caps. try adding layers of tape/cloth onto the thread caps to make it easier to unscrew.

SOURCE: How do you sight it true for the rifles prior to

You can get a base line by bore sighting the scope. Bore sight kits are a bit pricy, might be best to take it to a gun range an start at 15 yards shoot a few move out to 25 the 50 then 100. Yes your scope should be sighted for one gun one round, with a cold barrel. Let it cool between shots.  

SOURCE: scope will not bore site.

The sighting sounds about right to me meaning to you need to adjust the cross hairs i the opposite direction to where your point of aim is. If your sight is off 1/4 inch to the left you need to bring the barrel to the right to compensate and that's what the bore scope/site is doing. Think opposite and you'll have that tuned in a few seconds. I don't doubt that you have the correct mounting hardware BUT, it's from center bore to center scope what 2 inches so at 25'? Depending on what caliber I'd say at 25' you need to hold 2 inches high for center target. I'll just guess that you might not be able to get a zero until say about 25 yards with a 22 short. A larger bore/caliber will extend this out to possibly 100 yards.
I'm going to give you a link to a bullet trajectory chart so you can sort of see what it is I'm trying to write. you may need to cut and past this in your browser window.

http://www.chuckhawks.com/rifle_trajectory_table.htm

Here is another chart that shows a bullet drop from the muzzle.

http://www.chuckhawks.com/bullet_trajectory.htm

Hope this was a help have fun and be safe

SOURCE: I have a tasco 3x9x50 world class rifle scope. The

Try some PB Blaster. Wet a q tip and apply to the area at the base of the turret caps. Wait a few minutes and reapply. Then using a small pair of vice grips attempt to twist the turret covers off. A cotton cloth will help keep the gripping surfaces of the pliers from scratching too bad. Hope this helps.