Scope adjustment

A 20 moa rail means there is now a cant on your scope (scope physically point down in relation to the rifle bore) raising point of impact by 20" at 100yds.

In a perfect world you could pull the scope from you AR, and give it 20 MOA of clicks DOWN to be on at thd same range. In reality theres enough variables (unless your amazingly lucky) that youll have to re-sight from scratch....and you may not have enough elevation adjustment to GET to poa at 100yds, tho you should.

20 moa at 100yds is 20+", drop for most 55gr .223 at 200yd is about 4" or less. So it comes down to what you have on the DPMS right now, but assuming it's low base mounts, then you will have to adjust zero down at least 8 to 10 clicks at 200yds, probably more like 16 to 20 clicks depending if your scope is 1/4" or 1/2" /click at 100yds

Swap the scope, bore sight it, shoot the rifle and see where you’re at.

The 20MOA rail is to get you extra elevation when you're shooting way out there so you don't bottom out your scope.

Sight in process is the same as normal. Bore sight it and adjust at 100yrds, then walk out back to 200yrds if that's where you want to be. The extra 20MOA isn't needed at those ranges, but it dosen't hurt anything either.

All actions are not square, lots of scopes don't move to their advertised numbers, or the adjustments are not repeatable and I'm sure all bases are not made accurately. Actually trying it would be the only sure way to know.

hnusz said:

Just got a new to me savage 110fp in 223 . Gentlemen I got it from said it has a 20moa rail on it. I have a scope on my ar sighted in for golf balls at 100 yards. Ar is a dpms . How much would I have to adjust the scope or can I just move to the 200 yard bench. That's were I'm going to end up eventually. Thanks

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You could remove the rail and look at the underside for a conformation 20 moa stamped on it.
As posted there is no need for it on short to mid range shooting. Only a pita at short range restricting internal windage adjustments when bottomed out

Lots of “no” on this post.

It sounds like you are wanting to move a scope from one rifle to another. This will require completely rezeroing the optic to the new rifle.

No, you can’t simply move from 100 to 200yrds and expect a 20moa rail to bring a scope zeroed for one rifle at 100yrds to proper zero on a different rifle at 200yrds. There is only ~1.5moa difference between 100 and 200yrds for a 223rem, so a 20moa rail will make far too much change.

Rifle scopes are adjustable because they must be adjusted to uniquely zero on every individual rifle.

THAT SAID....

When using quality optic mounts on a well built rifle, in general you should be able to optically center the scope for windage and elevation (appropriately accommodating an integral zero stop if present, of course), mount onto the rifle, dial the elevation up for the height of the optic over the bore (typically 1.5-2.6”, depending upon mount), and then dial up another 1.5moa. Typically a totally around 3-3.5moa UP from optical center. This will be on paper at 50yrds for a level scope base. For a 20moa base, dial DOWN 16.5-17moa (+3.5moa-20moa = -16.5moa).

So... transferring the scope from the AR to the bolt gun, you should be able to dial off the difference in scope mount height, then add the 20moa correction, and you’d be on paper at 50yrds. Won’t be on target, won’t be zeroed, but it’ll be on paper enough to quickly rezero...

THAT ALSO SAID....

Mount the scope, optically center windage and elevation, dial up 3-3.5moa and you’ll be on paper at 50yrds, and zeroed at 100yrds within 5-8 shots.

Or...

Mount the scope, pull the bolt from the rifle, bore sight the scope on a 25-50yrd target, and you’ll be on target at 50yrds, again zeroed at 100yrds within 5-8 shots.

Or...

Mount the scope, use a laser boresighter to zero the scope ~1.5” high of the dot at 10yrds, and you’ll be on target at 50yrds, again zeroed at 100yrds within 5-8 shots.

Buy a 2nd scope for the Savage and keep the scoped AR as is.

Out

cdb1 said:

Swap the scope, bore sight it, shoot the rifle and see where you’re at.

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What this guy said- but get it on paper at 25 yards first.

FL-NC said:

What this guy said- but get it on paper at 25 yards first.

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I always start at 25 yards.

Your AR and your Savage 110 will not shoot the same even if you are shooting the same .223 rounds on both rifles. The chambers are slightly difference in size, for the AR than the Savage 110. Also you have to consider length of barrel and rifle twist. A difference in barrel length for one inch can affect velocity by as much as 25 to 50 fps per inch, affecting point of impact, I highly
recommend what cdb1 stated on his posts. Get your rifle bore sighted and re-zero, start at 25 yards.

cdb1 said:

Swap the scope, bore sight it, shoot the rifle and see where you’re at.

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Ditto that. The easiest way of transferring a scope from one rifle to another is to just zero the scope turrets and start from scratch on the new rifle. Don't ask me how many times I've done it. Sometimes I think I've spent more time mounting, sighting and zeroing scopes than just plain shooting because I keep changing my mind which scope I want on which rifle. Honestly, my preferred method now is when I have a scope that works the way I want it with one rifle I just leave it there, and if another rifle needs a scope I buy a new scope for it.

If you are going to use the AR with a scope I agree with the guys it is going to be a big hassle to switch back and forth. Just get another scope for the Savage. Also you can replace the 20 MOA base with a standard base which will mean less adjusting.

You also could buy a set of Burris Signature Z Rings with the inserts and correct the set up to effectively being a 0 MOA Rail. I use them on most of my rifles and as a added benefit they eliminate ring marks.

Bob

rkittine said:

You also could buy a set of Burris Signature Z Rings with the inserts and correct the set up to effectively being a 0 MOA Rail. I use them on most of my rifles and as a added benefit they eliminate ring marks.

Bob

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Why would you offset the offset? If you want a flat rail, get a flat rail. But I don’t see the point in countering the offset with another offset device.

If you want 0 MOA and only 0 MOA I would agree just put a new rail on. If you want to radically change point of impact, then having the inserts allow an easy way to shoot 100 yards one day and 1,000 the next.

Bob

rkittine said:

If you want 0 MOA and only 0 MOA I would agree just put a new rail on. If you want to radically change point of impact, then having the inserts allow an easy way to shoot 100 yards one day and 1,000 the next.

Bob

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If you’re putting a -20 ring insert on top of a +20 rail, you’re netting 0 MOA, which removes the ability to utilize the maximum potential adjustment of your optic. Like I said before, it doesn’t make sense. If a flat rail doesn’t get your load to 1,000, then putting a -20 on top of a +20 doesn’t either. The rail OR the ring inserts are designed to independently or COLLABORATIVELY promote this advantage - not to contradict eachother.

It’s like putting body lift blocks under a car and then doing a spring lowering job with the intent to increase your clearance. The wheels and running gear didn’t move relative to the ground, so you didn’t gain anything and spent money to do it... I gotta be missing something here.

For the record, I do use a lot of the Burris Signature Zee and Xtreme Tactical rings with their inserts, for the purpose of longer range reach. I’m not averse to the idea here. It just doesn’t make sense to spend money for +20 just to spend more money for -20 instead of simply zeroing at the +20 and taking the gift of extended range.

hnusz said:

Thanks for all the replies. Works crazy right now. The guy that I bought it from said it was a Warne 20moa steel rail it is steel haven't had time to pull it off maybe this weekend. I'm betting it is you can see a difference in height front to back . Probably put a flat rail on it range I shoot at is only 200 yards. Just wanting to see how it shoots before I buy a new scope.

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There's really no reason to change rail most scopes have well over 20moa of adjustment, the 20 moa mount just puts the scopes adjustment range 20 moa higher.
Since most scopes are designed to be near the center of their adjustment a scope with 60moa vertical should in theory be able to dial ~30 moa up or down from a 100 yard zero with a 20moa rail you should be able to dial 50moa up and 10moa down.
There's really no reason to dial down from a 100 yard zero.

Again, if you are only in need of one MOA set up, put on what makes sense The inserts included with the rings are not just -20 MOA. They can be set up to increase the 20 MOA to 30+ for shooting 1,000 yard or reduce in a number of different steps. My 6mmBR Norma takes about 39 MOA to make it to 1,000 yards when sighted in at 100. I like to have my scopes dialed somewhere in the mid range of the adjustments even we I can crank in all I might need to change yardage. I have a number of rifles that I shoot at very different yardages and with rails loctited on, I prefer just changing inserts and it also eliminate ring marks on the scopes.

I shoot my 1,000 yard rifles at my home club from time to time where I only have 200 yards to work with. All three of them are set up with 20 MOA (and one with 30) Rails and rather then changing rails, I just change inserts.

You can also buy rings that have offsets built into them to be used on 0 MOA Bases, but based on the geometry they can very easily leave ring marks on the scope.

Bob

mavracer said:

There's really no reason to change rail most scopes have well over 20moa of adjustment

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Typically, using a 20moa rail will require a scope to have (roughly) 40moa of internal span. Which MOST do.

As I described above - an optically centered scope in good rings on a good rifle will align parallel to the bore axis when mounted. Dial up the optic height (crossing X of line of sights for scope and barrel at 100), dial up some more about 1.5moa for gravitational drop at 100yrds (replacing the straight X with the ( shape of the actual trajectory) and you’ll be near center on paper at 100. So for a 2” high scope, that’s 3.5moa up correction from optical center. If you have 20moa internal, optical center is 10moa, and 100yrd zero is approximately 6.5moa from bottom - 13.5 from top. Can’t fit a 20moa rail in here. With a 40moa internal scope, optical center is 20 from bottom, and 100yrd zero is approx 16.5 from bottom, 23.5 from top... so a 20moa rail sticks you 3.5 from the top and 36.5 from bottom - about 900yrds with a 6.5 Grendel, as an example...