school me on 20 moa bases

4

42769vette

Guest
im trying to decide on what bases to put on a 1000 yd rifle. its a 260 and im using a scope with 120 moa adjustment. i dont think i need a tapered base am i right? i think that if i were to get lucky and get the exact mechanical zero at 100 yds (i know it wont actually happen) that would still give me 60 moa adjustment wich should get me well beond the 1000yd marker. this is all what im thinking but in new to shooting this range so feel free to correct me if im mistaken

this will be on a win model 70. anyone recomend a certain brand or have a opinion on what brand to stay away from. also anone know where i can find a sale on one.

also do i need 20 moa bases. could i use a leupold base or somthing along those lines
 
I'm no expert on optics or bases, but here is (my 2 cents worth) the way I rationalize using a 20 MOA base for 1,000 yds. Image a circle the diameter of your 120 MOA (480 clicks if 1/4 click value), now image a square inside that circle of about 340 clicks length and wide. Your scope adjusts up and down and left and right so you get your best tracking is in that square. If you are centered for elevation at 240 clicks in the circle you are centered at 170 in the square and can go up 170 clicks or 42.5 MOA, but if you use a 20 MOA base you could go up 62.5 MOA (20 + 42.5) if necessary or save cranking your scope up 20 of the 42.5 MOA (42.5 - 20).

Example: I shoot an 87 gr bullet at 2900 fps from my 6mm BR zeroed at 200 yds. The adjustment for 1,000 yds is +118 clicks or a 236 click square (2 X the longest adjustment from center, which is +118), but by using the 20 MOA base I'm shooting in a 160 click square (2 X the longest adjustment from center, which is -80 to get back to the 200 yd zero) You still have to click +118 for 1,000 yds, but you start from -80 now. Assuming I've started from the optical center for elevation. In my mind the less work you make your scope do the better and tracking is best from the center.

I use a one piece 20 MOA base with windage adjustment and optically center my scope and then bore-sight it with the base only.

I'm sure I've opened a can of worms here and someone is sure to correct me, but discussion is good for learning and I'm still learning.
 
It is generally conceded that the center of the optic gives you the best resolution of the target. You get the broadest adjustment the closer to the center of adjustment.

My two cents on these bases has been my greatest luck has been with this fellow. They come to me absolutely perfect for the job at hand.http://www.nearmfg.com/


I have had the vary best luck with this gentleman.:D
 
I really don't like the idea of cranking a scope back and forth between short and long range (100 - 1000 yards) but I suppose nothing is really harmed. As Al said, your best resolution is at the center of a scopes center, which is why most 1000 yard shooters will opt for a tapered base and/or rings.

If you are bound and determined to crank up and down you need to be aware that you may be compromising a certain amount of resolution. A much better set up would be to have the optical center at a mid-range, say 600 yards. That way you would be using more of the scopes optics as compared with a 100 yard set-up where you are actually only using 1/2 of the scope.

Understand?

Ray
 
Check out the Burris Signature line of rings. They use plastic inserts and Burris offers a set of inserts with various offsets. I am using these rings on a 22 LR that is used for long range silhouette shooting [ 188 meter Rams :eek:]. I am using the .020" offset bushings.
 
+1 on the EGW....

I put one on a 6.5mm-06 I just built. I don't know what it lacks compared to the bases that cost three times more, but it works just fine. I used a 0 moa (no taper) for my Weaver T-36 and have no problem getting to 1000 yds. Maybe I should have used 20 moa but, I haven't had any problems.

Hope this helps,
Med.
 
42769vette said:
im trying to decide on what bases to put on a 1000 yd rifle. its a 260 and im using a scope with 120 moa adjustment. i dont think i need a tapered base am i right? i think that if i were to get lucky and get the exact mechanical zero at 100 yds (i know it wont actually happen) that would still give me 60 moa adjustment wich should get me well beond the 1000yd marker. this is all what im thinking but in new to shooting this range so feel free to correct me if im mistaken

this will be on a win model 70. anyone recomend a certain brand or have a opinion on what brand to stay away from. also anone know where i can find a sale on one.

also do i need 20 moa bases. could i use a leupold base or somthing along those lines
Click to expand...


If your set on "exactness" here's what I'd do:

Shoot the rifle at 100 yards. Record the velocity of the bullet.
Crunch the numbers through some software and see exactly what your drop is at 1000 yards.
Buy or have a base made that will accommodate that amount of drop so that the lenses in your scope stay close to their mechanical zero.

Here's why. As with anything that has to do with light, the more bending, kinking, finessing a guy does with an image, the more prone to error it is. I don't want to sound alarming as quality optics these days are quite good, but if you want every last little photon of image purity then this would be how I'd do it.

Hope that helped.

C
 
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