Got my new sights......question

acrybb · Post by **acrybb** » Sun Dec 02, 2012 6:27 pm

I just bought some new sights & raisers.

The raiser allows me the ability to move the sight over to either side by 4mm. I thought that's great. It means the sight will fall more naturally on the eye. However I am now thinking. If both front & rear sights are 4mm off centre in order to have the rifle shooting where I'm aiming will I not then need to adjust it 4mm back across?

I'm kinda split on this one as at the same time I'm thinking no because the front sight does not move I would actually need to move it more left so that the line from the rear sight to front sight to POI crosses the pellets line.

Someone please help my brain out. Apologies for the night shift brain.

Thanks
Andy

mtncwru · Post by **mtncwru** » Sun Dec 02, 2012 8:53 pm

According to my math your front sight would need to be 0.328mm closer to center than your rear sight and still have them point to the same place as your barrel. This assumes a sight radius of 850mm, a total distance from rear sight to target of 10.35m, and a 4mm offset from center for your rear sight.

And I completely understand about night-shift brain. I still remember the clarity that going to day shift brought, and I still wonder how I functioned for so many years on nights.

acrybb · Post by **acrybb** » Sun Dec 02, 2012 9:06 pm

So the answer is that I don't need to move the sight 4mm then lol only about .3mm :).

Have a bore laser coming that will get me in the ball park they are not the greatest of tools. Although I would have to use it at the distance I would intend to be shooting as I'm introducing a new horizontal error which will change as once the paths of the sight and shot cross. So no point in bore sighting at a few metres as it will be well out at 10?

mtncwru · Post by **mtncwru** » Sun Dec 02, 2012 9:31 pm

My advice would be to stop attempting to reason out complex geometric relationships with a night-shift IQ. Think about this later when you've had some sleep and a decent bit of coffee.

I should have asked: what discipline do you shoot and at what distances? You said "pellet" so I assumed 10m air, which was the basis for all my calculations.

mtncwru · Post by **mtncwru** » Sun Dec 02, 2012 9:32 pm

And if you're curious, here's the setup I used. I just made it a similar triangle problem (which it is), and solved for x.

acrybb · Post by **acrybb** » Sun Dec 02, 2012 9:34 pm

When you say sight radius. I assume this to be the visible area through the sight? I'm new to this so forgive the question.

Thanks
Andy

acrybb · Post by **acrybb** » Sun Dec 02, 2012 9:37 pm

Ah cool ill get a look at your attachment in the morning makes a bit more sense. 850mm distance between sights :).

Thanks for your help :)
Andy

acrybb · Post by **acrybb** » Mon Dec 03, 2012 5:04 am

thanks i understand now. well, im not gonna pretend i understand the maths ;) but i see what your doing. basically the foresight is a pivot point which the hypotenuse of the triangle goes through from the rear sight to POI. So because the is a small distance between the front & Rear sight any movement here is amplified at the longer foresight to POI distance. So in theory if my sights are at the moment absolutely bang on with a pellet shift of 0.16mm per click i would want to move my sight 2 clicks left?

I assume that the same wouldnt be true for elevation as you would then have a whole new factor of pellet drop to consider. however if this wasnt a factor would i be moving the rear sight up approx 4-5 clicks if it was on a 10mm raiser?

Andy

mtncwru · Post by **mtncwru** » Mon Dec 03, 2012 10:18 am

Your estimate on rear sight adjustment with a 10mm riser sounds about right. You should be able to compensate for the necessary difference in offset/height just by clicking your rear sight. You will have to re-sight your rifle, and that may require more than the few clicks discussed, simply because of how the sights sit on the risers. But in terms of compensating for the difference in necessary offset (horizontal) or stack (vertical) between front and rear, your rear sight should be able to do that easily.

acrybb · Post by **acrybb** » Mon Dec 03, 2012 10:36 am

Ok,

Thanks very much for your help :). Hopefully the new sights will help me find the target a bit easier :)

Thanks again
Andy