Which minute of angle rail?

K

kchw7gsv

Guest
I am switching a point blank BR rifle into a dedicated 600 yard BR rifle- (non-competition). I will be shooting 6Br, 95 gr bullets @ approximately 3000 fps, and will be using my Leupold 45X comp scope.
My question: Should I purchase a 10 moa or a 20 moa tapered base? I will probably use Burris 30 mm scope rings. The 30 mm rings have +- 10 moa inserts if needed.
My search results mostly came up with 20 moa rails for all long range shooting?

Thanks
Kurt
 
Kurt,

There's a good argument that the optimum rail is the one that leaves your scope at the optical centre (which is hopefully also the mechanical centre) at the longest distance that you plan to use it - as long as that allows you the capacity to adjust to other distances you expect to shoot it at as well. This condition allows for both elevation & windage adjustments to operate at best possible efficiency. In your case, you will be OK with the scope centered at 600 because you should have enough adjustment to get back to 100/200 where maybe you'll be starting your load testing.

It would get a tad more complicated if you decide you want to shoot a bit of 1000 yard as well because you would have to compromise because of available adjustment. For example, I use an 8-32 NF BR on my rifle I shoot at 1000 to 1200 yards. The rail has been cut so 1100 yards is at optical/mechanical zero but when I load test at 100 yards, I have to catch my groups somewhat above the 100 yard zero.

John
 
I think I understand what you mean, but I am not sure how to do it.

Kurt
 
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IIRC, 600 yards is *about* 14 minutes up from 100. It will be slightly different depending on what you shoot. You could go to the JBM site & calculate it real close...

But it's going to be right in between 10 and 20 MOA I believe you can use a -10 on the front ring, and a +5 on the rear with the Burris rings. If you do that, you won't need any taper in the base, and should be pretty close.
 
The Burris 30mm Sig Zee rings only come with 0 and + - .01 inserts. It may be possible to get a + - .005 angle by useing a 0 insert in the rear ring and a -.01 front bottom + .01 top tho. Burris 1" is available with 0, + -.005, + -.01, + -.02
 
Thanks for the imput-

Since I have to use a BAT specific mount, I think I'll go with a 10 MOA riser. With the Burris system I think I can make it work at 100 / 600 yards. I do think it would work with non-tapered mounts. Leupold told me that my 45x45 scope has 38 MOA "total" adjustment. I am guessing that I could use 10 MOA and still stay pretty centered.

Kurt
 
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Hi Kurt.....another way of thinking about it is........how many moa UP are left when your rifle is zeroed at 100yds.???? ..then you will need aprox 12-14 moa to get zeroed at 600.....you may have enuff ...but if your about out of travel then 10 would bring you down a lil' and still allow you to get bak to 100.......however if you ever shoot at 1000 you prolly will need 20.....that is the trubl with scopes with only 40 moa ,,or less ...of travel........those are great scopes and I use one at 600 and 1000,,,but you gota see if the travel is there before u buy the wrong base or get to the event and realize your gona hav to hold on a rock or tree root above the target!!!....hope this helps muddy the water....Roger
 
expiper-

I am waiting for my new reamer, so I do have time to do some checking. I shoot mostly 100 yards with ppc, so maybe the next warm day I will try your suggestion.
With 1/8 clicks, I think I would have to go up at least 100 clicks. If I did my calculations correctly I think I need to be 13.8" high at 100 yards to be dead on at 600 yards.

Kurt
 
Kurt ....start thinkin in moa's or inches ....the numbers are on the turrets to simplify your come up's.....its tuff to go up 103 and then bak down 41 and bak up 37.....get it??!!....get a 100 yd zero and zero the turrets there....then no matter where u go up-n-down its much simpler to keep it in your mind and with your charts ...tape one to the stock/scope ,,,somewher on the gun visible while in shooting position...Roger
 
To answer your original question: If this rifle will be limited to 600 yard shooting -- with no 1,000 yard shooting -- I would use a 10 MOA rail, not a 20 MOA rail. If you want to allow for the possibiity of 1,000 yards, I'd make up, or have made up, a 15 MOA rail for the BAT.

Also, if you're not going to be shooting at 100 yards for anything but testing, I would also make up a "testing" target, with an IBS 50-yard rimfire target taped sideways at the bottom, and a blank place to paste plain white paper where the bullet will impact. That way, you don't have to change the sight. For me and 1,000 yard shooting, the top of the impact area is about 28 inches above the top row of bulls. A 1.5 to 2 foot wide by 3.5 to four foot tall piece of coroplast will hold everything, and last for several years worth of testing. 200 and 300 yards is harder, as the bullet will strike farther away from the aiming point.
 
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I appreciate the helpful replies...... I know quite a few of the custom bullet makers who produce the point-blank BR bullets, but now I need to purchase some 80 to 100 grain custom 6mm bullets.
I have some Berger’s and want to try some Bib’s. Any other suggestions?

Kurt
 
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