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20MOA bases too much?

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Unread 02-10-2004, 12:35 AM
rjb rjb is offline
Junior Member
Join Date: Feb 2003
Location: Toledo Ohio
Posts: 20
Re: 20MOA bases too much?

The 20 minute rails are used particularily at 1000 yds target shooting so as to raise the cross hairs in elevation AND leave travel in windage for wind comp. The adjustments on most scope are not rectangular. SO at extreme ends of adjustment
up/down, left/right the cross direction is restricted. Therefore it depends on which scope your using. Some Leupolds have +/- 50
minutes travel (takes 308WIN/175 SMK ~34 minutes elv. for 1000yds) A Tasco scope may only have +/- 12&1/2 minutes. so you see the equpiment dependancy. rjb
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Unread 02-10-2004, 09:12 AM
rjb rjb is offline
Junior Member
Join Date: Feb 2003
Location: Toledo Ohio
Posts: 20
Re: 20MOA bases too much?

Not mentioned in above post is that one can use scope rings to compensate or adjust scope
from out side, This saves interal adjustments for wind etc. I believe Harrel
1 piece rails can be had in 15 or 20 minute
angle. The rings mentioned are the Burris
Signature rings with plactic inserts. While
scope tilt can be done with these rings they
also offer an alternative. That is perhaps
if tapped holes in action or barrel intallation adds up off center bullet impact.
The Burris rings can be used to center scope tube in both elevation and windage from outside. May sound like a lot of fussing. Butt consider what we pay for good scope is should be mounted so it can do it's thing.
Note to "see" how close the crosshair image
is off center do this. Take small cardboard box and cut two Vs in oposed sides to support
your scope. Set up a white plane surface lighted in from of scope and then look throught as you slowly rotate the scope. If you desire a true starting point adjust the knobs until the crosshairs do not appear to
wobble as tube is spun. THIS is the scopes
natural Zero. Keep the same knob settings (or on some scope you can readjust the knobs with allen wrench to TRUE zero). To continue the experiment reinstall scope on rifle and
fire a group at large paper at 100 yds. What
all this will show is how much drift is in mounting. Most people pop a scope on a rifle and "go zero it in" that's fine for the deer woods where the caps on the adjustments may never come off again. But for outwest or actual long range hunting they may find the mounts can help with elevation or if scpoe in cockeyed on action most of windage etc. in one direction was used up on "zeroing in". The wind has been known to blow both ways (sometimes at same time at long range) So knowing the exact amount of scope adjustment and how to use chart info might
make your day rjb [img]images/icons/wink.gif[/img]
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Unread 02-10-2004, 10:51 AM
Silver Member
Join Date: Nov 2003
Location: South central Montana
Posts: 129
Re: 20MOA bases too much?

has anyone seen or used the Mamba one-piece scope mounts with 25 moa slope built in? I see them advertised in the MidSouth Shooters Supply catalog for $139.99
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Unread 02-10-2004, 05:02 PM
Platinum Member
Join Date: Jun 2007
Posts: 1,519
Re: 20MOA bases too much?

Express. I hope this helps.

Your nightforce scope should have about 100 MOA of TOTAL adjustment of elevation so lets use that for this example.

Lets say that you mount your scope with standard rings and bases. Next lets say that you are lucky enough to shoot a group that is right on the bullseye at 100 yards with your elevation knob opticaly centered. That means you can dial your knob down 50 MOA (inches) or up 50 MOA (inches) at 100 yards.

Now you re mount your scope with 20 MOA bases OR rings. Next you adjust your elevation knob to shoot the bullseye at 100 yards again.

You will have 70 MOA of upward adjustment and 30 MOA down adjustment and you can still Zero at 100 yards.

Now lets say you re mount your scope with the night force 40 MOA base and re adjust for 0 at 100 yards.

You will have 90 MOA up and 10 MOA down and still be zeroed at 100 yards.

Also, as mentioned earlier, your sight picture will always look the same.

I was able to shoot to about 850 yards with regular rings and bases out of my .308 and leopold scope adjusted all the way up. Then I had gunsmith darryl holland make a one piece base/ring type of mount with what he thought was the appropriate taper.

I believe it is around 20MOA but I don't know for sure. I do know that with my elevation turned all the way up I can shoot the crosshairs at 1100 yards and still can adjust back to have a 100 yard zero (or less if I want).
GRAVITY. It's not just a good idea. It's the LAW!
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Unread 02-11-2004, 04:35 AM
Silver Member
Join Date: Jun 2003
Location: Aussie in Italy
Posts: 433
Re: 20MOA bases too much?

4Ken Horn, thanks for your reply.

It doesn't look like I will have any great problems at this point; I don't care for using clicks to make adjustments, rather prefer to use the reticle for reference in holdover and establish where my impact points are along the NP-R2 reticle. At the moment I use a scope with the NP- 1RR and find it to be very good.

The only drawback is that it will only work on pre established settings (from memory at 22x for this particular model)

rjb tells us that he needs apporxamantly 34MOA of adjustment for a 1K zero so it looks like I should have enough room to do so should I desire.
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