MOA scope bases

Clobbersauras

Clobbersauras

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Hi All! Just a question for all you long range guru's. How many degrees off horizontal does a 20 MOA base have to be to be manufactured correctly? Is there a formula for this that anyone has handy? I've always wondered how this is calculated.

Cheers,
Clobb
 
If you have a base that is 200mm long and you want it to slant 20min you can calculate the difference in thickness from end to end using Trigonomentry.I get 1.164mm.I"m not sure if this is what the factory 20min bases are or if they calculate somethingelse into it.
 
GAIRLOCHIAN said:
If you have a base that is 200mm long and you want it to slant 20min you can calculate the difference in thickness from end to end using Trigonomentry.I get 1.164mm.I"m not sure if this is what the factory 20min bases are or if they calculate somethingelse into it.
Click to expand...

Thanks for that, do you have the trig equation you used? (I wish I remember all my trig classes now - who knew I'd actually find a use for it):D.
 
A very simple, and I emphasis simple, rule of thumb is 1 thou raised on a standard action yields 1" at 100yds.

Of course, there are many variables like actual base length vs scope height vs true scope POA vs etc.

But it will give you a ballpark way to shim a scope base.

I did find it to work enough to get me close.

This principle also works for adjusting the Burris ring inserts.

Are you making a canted scope base or just shimming a 1 pc base?
Jerry
 
Like Jerry said
I think what they are all telling you is from one end to the other of a 6 inch base, there should be 20 thou of an inch difference. = 20MOA
I could be wrong, though.
 
mysticplayer said:
A very simple, and I emphasis simple, rule of thumb is 1 thou raised on a standard action yields 1" at 100yds.

Of course, there are many variables like actual base length vs scope height vs true scope POA vs etc.

But it will give you a ballpark way to shim a scope base.

I did find it to work enough to get me close.

This principle also works for adjusting the Burris ring inserts.

Are you making a canted scope base or just shimming a 1 pc base?
Jerry
Click to expand...

Well to be honest, I had an idea for a very simple adjustable MOA scope base:redface:. I saw the need for one when I tried to get my little BRNO 22lr to 200 yards. I would have loved to have an adjustable MOA base for that experiment instead of running out of elevation and having to hold over. I just needed to know how much physical height/angle adjustment would be needed. I don't even know if there is a market for such a thing and I'm new to the "long range" stuff. But I guess now that I've sprung for dealer status I should try to keep the ideas and projects coming.....;)
 
I have already designed and had one made. Works great. Approx 225mins of up so I can go from 100yds to 2300yds on mechanical up alone. I have since done a bit more machining to try and reach out to 2600/2700yds. Will know how it worked when the snow melts.

This is with my 6.5 Mystic and 139gr Lapuas.

The machinist did a great job of ensuring that the windage didn't change when the mount was locked up. Also, the adj's have been repeatable.

Didn't get a chance to do alot of dressing up. Marks and labeling are crude but it does allow for a whole bunch of up.

And yes, you will need to have the checkpiece move too or else your cheek will be well off the rest.

With both canted bases and the Burris rings, it is pretty easy for shooters to set up their scopes to get out to at least 1200yds. That is likely 3 times further then the average shooter shoots.

I had a pretty goofy 'zero' when I took my 223 to a mile but it was done without any fancy bases and a typical scope. I just shimmed a one piece base, used the Burris rings to fine tune the adjustments and the scope for the final yardages.

I have personally put the production of my mechanical base on hold as I see some awesome scopes coming with lots of internal adjustment. Way easier to use and more then enough up to get suitable cals to a mile.

That's likely far enough for most. However, look forward to see what creation you can come up with. There is always room for innovation and if the export of stuff stops, we will need manf right here at home.

We should have them here anyways...

Fun, fun, fun...

Jerry
 
mysticplayer said:
I have already designed and had one made. Works great. Approx 225mins of up so I can go from 100yds to 2300yds on mechanical up alone. I have since done a bit more machining to try and reach out to 2600/2700yds. Will know how it worked when the snow melts.

This is with my 6.5 Mystic and 139gr Lapuas.

The machinist did a great job of ensuring that the windage didn't change when the mount was locked up. Also, the adj's have been repeatable.

Didn't get a chance to do alot of dressing up. Marks and labeling are crude but it does allow for a whole bunch of up.

And yes, you will need to have the checkpiece move too or else your cheek will be well off the rest.

With both canted bases and the Burris rings, it is pretty easy for shooters to set up their scopes to get out to at least 1200yds. That is likely 3 times further then the average shooter shoots.

I had a pretty goofy 'zero' when I took my 223 to a mile but it was done without any fancy bases and a typical scope. I just shimmed a one piece base, used the Burris rings to fine tune the adjustments and the scope for the final yardages.

I have personally put the production of my mechanical base on hold as I see some awesome scopes coming with lots of internal adjustment. Way easier to use and more then enough up to get suitable cals to a mile.

That's likely far enough for most. However, look forward to see what creation you can come up with. There is always room for innovation and if the export of stuff stops, we will need manf right here at home.

We should have them here anyways...

Fun, fun, fun...

Jerry
Click to expand...

Thanks for your input Jerry, as always your responses are very informative. Given your assessment of the market, I'll probably shelve the idea into my dog eared idea book and revisit it later. I have more than enough to keep me busy;).
 
Post #2 nailed it. If your talking Burris rings then its different because you are actually changing the thickness, not the angle. Of course the angle changes as a result but the space between the rings varies. Mathematically its going to be close enough because we normally have the same general spacing. A tapered base is simply on an angle, the thickness change is irrelevant. Also, a Rem for example, has a lower rear bridge than the front :rolleyes: so the thickness difference is ... well different.
 
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