Advise on tr sights.

[Macca]

Hi. Iv e been going to start shooting both target rifle and f class for a while but haven't got the time so far. I have an omark in 223 that I wish to use for both. I had a 20 moa rail made for it for the f class side. Where I run into trouble is changing to my central rear sight. In order to clear the rail I can't come below about 40 moa of elevation.

Can you put a rear sight on the 20 moa rail. I imagine that wouldn't work because you would be looking through it at an angle. Any help would be good

[Barry Davies]

If you have enough elevation left in the Central sight you could fit a higher foresight block.
Barry

[Josh Cox]

Give John Cooper a call, I had the same problem with an Eliseo stock, he sold me an adjustable foresight. From my use on a 900mm sight radius 1 increment on the foresight equals 6 MOA.

http://oneoffprecision.com.au/2012/11/2 ... ion-sight/

Pictured here on my Mastin Stock.

[Macca]

So you do the course adjustment on the front sight for the different ranges and the fine adjustment while shooting on the rear sight?

[Josh Cox]

Course adjustments, in 6 MOA steps and fine on rear.

One of the guys at my club has a 30mm adjustable.

His zero (300m) is: 30 MOA on the TMAC, and 0 on the front ( the length of the slot in the TMAC will not allow him to set zero as his zero )

1000 yards is 34 MOA on the TMAC and 5 on the front ( 5 time six = 30 ). plus 4 on rear, plus 30 on front equal total of 34 MOA. Its pretty easy when you work it out and these sights put the rifle lower into your shoulder ( not sure if that is a good or bad thing ).

Here is mine, my numbers are different due to the rear sight being a Phoenix, but same concept.

The first set of elevations are from the Pesja spreadsheet ( based on sight radius of 736 mm), my numbers are actual and based on a 900mm sight radius.

2950 FPS Barnard
YDS M YDS M
MOA MOA MOA MOA
300 -1.0 0.0 12/-.5 12/0
400 3.0 4.0 12/2.5 12/3.5
500 7.0 8.0 13/0.0 13/1.5
600 11.0 13.0 13/5 14/ 1.5
700 16.0 19.0 14/3 15/1.5
800 21.0 25.0 15/4 16/ 1.5
900 28.0 32.5 16/2.25 17/ 2.0
1000 34.5 40.5 17/1 18/2

[Macca]

Ok cheers. I think I will just buy an adjustable 30 mm front sight and be done with it. Then I will just have to get an adjustable cheek piece and im ready to start shooting

[scott/r]

I'm gathering that the sight radius is the distance between your front and rear sight?

[Josh Cox]

Yes, from what I can gather, the elevation data is generally given on a sight radius of 736mm ( from foresight element to rear iris ), most rifles now have a sight radius of circa 900mm.

736 / 900 = .818, so one minutes worth of clicks, be it wind or elevation will be actually less.

[scott/r]

Cool. Makes sense. Thanks.

[bsouthernau]

Why not just take the scope base off when you want to use the iron sights. That's what I do - it takes very little time and you won't have to put the cheekpiece up so high.

Barry

[Macca]

Why not just take the scope base off when you want to use the iron sights. That's what I do - it takes very little time and you won't have to put the cheekpiece up so high.

Barry

because the bolts holding the scope base on bolt into the action. Something only has to go wrong once and the thread gets damaged inn the action. If you are doing it all the time I don't like this idea. I'm already down to 3 bolts because i have a picatinny rail fitted and the rifle had 2 piece bases on and the original holes interfered with mounting it

[Razer]

One good thing about Omark actions is, that comparatively, the metal is not that hard.
If you strip a thread, then you can just drill and tap in a slightly larger one.
Use a torque wrench as bolts/screws only get stripped by ham-fisted people applying too much grunt.

[sncltu]

In the absence of a photo of your action with scope rail attached I'm going to ask why it is that you don't simply move the rail forward an inch or three and use a Central sight plate to mount the TR sight when not using the scope? IMHO this would be by far a more cost effective fix than going the adjustable f'sight route.
If the mounting screws on the rail do not align with the holes that are currently tapped then I'm sure that would be an easy fix - simply tap another one or two into the rail at the appropriate points.

FYI and just by way of letting you know that this is not idle conjecture on my part I have a dovetail fitted to one of my actions which I use for both TR and F Class. The dovetail ( Anschutz) serves for mounting both my scope as well as my Centra (not to be confused with Central) TR sight (which is also an Anschutz dovetail mount). Let me know if you're interested and I'll email a pic.

Hope this helps

[Macca]

How much advantage is 30 mm front sight. I can get a cooper adjustable 22mm sight for 230 or 400 for a 30mm. Given my eye sight isn't the best how much advantage would the 30mm be

[sncltu]

"How much advantage is 30 mm front sight. I can get a cooper adjustable 22mm sight for 230 or 400 for a 30mm. Given my eye sight isn't the best how much advantage would the 30mm be?"


I have two 30mm tubes sitting in the cupboard gathering dust and have gone back to shooting with the 22mm which I much prefer. In hindsight I should have saved the money and not gone with the 30mm. Hope that answers your question.