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View Full Version : Bolt guns - 20 MOA base or higher rings / mount?


RHINOWSO
10-01-12, 11:21
Long story short, I'm getting into the precision rifle thing. I have a Remington 700 AAC-SD on layaway and am pondering how I want it to be set up. I'm looking to press long range shooting, out to 1000m and am considering a number of scopes.

I researching, I see that some people go with a 20 MOA base to give more elevation available for adjustments / holdovers at longer distances... I was wondering what (if anything) was the difference in doing this or just going with a higher set of rings / mounting system.

Also, as I understand it the 20 MOA bases simply raise the height of the scope - or do they actually have a upward rise from back to front, although I'm pretty sure they don't.

Thanks for the help, I looked around here and the interweb but couldn't find a definitive answer - it looks like most people go with a 20 MOA mount and lower rings, and the use of a QD mount system is very rare. I'd like the option of taking the scope to other guns occasionally, so a ADM mount of some type might be the way I go - depending on the the power of the scope I end up getting, that is.

Rhino
Jack-O
10-01-12, 11:55
no, the 20moa base when installed correctly, provides an angular increase of 20 MOA over standard rings. this allows calibers like the 308 to get enough elevation at longer ranges without having to rely on the extremes of scope adjustment. some scopes just dont have enough elevation, and this rail helps.

in short, it's sloped
RHINOWSO
10-01-12, 15:15
Thanks.
markm
10-01-12, 15:35
I originally had a standard base on my 20" rem 700 .308. Then I switched scopes to a Bushnell Elite Tactical. That scope would run out of elevation when shooting 1000 yards. So I had to buy a 20 MOA base.

Interestingly enough, when I swapped the base, my POI moved 24 inches high at 100 with minimal windage adjustment needed.
Inuvik
10-01-12, 15:47
it looks like most people go with a 20 MOA mount and lower rings, and the use of a QD mount system is very rare. I'd like the option of taking the scope to other guns occasionally, so a ADM mount of some type might be the way I go - depending on the the power of the scope I end up getting, that is.

Rhino

I am just starting to research a build myself, and noticed the same thing. Is there some specific disadvantage to a one-piece (Larue SPR) type scope mount/rings other than the price? Is it just pointless given the cost vs. return on a bolt gun?
mikeith
10-01-12, 15:57
I am just starting to research a build myself, and noticed the same thing. Is there some specific disadvantage to a one-piece (Larue SPR) type scope mount/rings other than the price? Is it just pointless given the cost vs. return on a bolt gun?

I've been told that the better QD one piece mounts out there are spot on. It's a matter of making sure you are consistent in remounting it (base pushed forward tight against the picatinny rail)

I'm going this route as well because I'm buying my first really nice scope and want to be able to use it on more than one platform with more ease
RyanB
10-01-12, 16:00
QD is useful on an AR and one piece is necessary to get the front ring out over the handguard.

If you're using a 30mm scope on a 700, look at the Nightforce unimount. Fewer parts, cheaper than a ring plus a base and you can mount a level to it.
Inuvik
10-01-12, 16:14
QD is useful on an AR and one piece is necessary to get the front ring out over the handguard.

If you're using a 30mm scope on a 700, look at the Nightforce unimount. Fewer parts, cheaper than a ring plus a base and you can mount a level to it.

Pardon my ignorance, but if you utilize the Unimount on a 700 with a 20 MOA rail, will you not have 40 MOA total to adjust for? Would that be an issue at closer ranges?

http://nightforceoptics.com/unimount/

Also, Is there a difference (other than brand preference) between the function of the NF mount and this Larue?

http://www.laruetactical.com/lt120
RyanB
10-01-12, 16:52
My apologies, I meant the direct mount.
RHINOWSO
10-01-12, 18:59
My apologies, I meant the direct mount.
Looks interesting and something I'll take a look at. Probably going with a Viper PST 6-24x50. I have no problem laying out the cash for a NF or other scope, but want something entry level to start off with and as I shoot, see what else is out there.

Thanks for all the replies.

Rhino
Ring
10-01-12, 19:15
Pardon my ignorance, but if you utilize the Unimount on a 700 with a 20 MOA rail, will you not have 40 MOA total to adjust for? Would that be an issue at closer ranges?

http://nightforceoptics.com/unimount/

Also, Is there a difference (other than brand preference) between the function of the NF mount and this Larue?

http://www.laruetactical.com/lt120

depends on the scope... i have a razor and have it on a 20moa base with a 20moa QD mount, so 40moa total.. i have a 100y Z and can dial to 2000y with that set up...
CLJ94104
10-01-12, 19:15
Look at the EGW 20moa 1 piece HD base for a 700. Seems to be a match made in heaven.
RHINOWSO
10-01-12, 19:19
Ring - any chance of a photo of your rig?
Ring
10-01-12, 19:53
Ring - any chance of a photo of your rig?

http://i.minus.com/jbbe5ekbKtTKc.JPG (http://minus.com/lbbe5ekbKtTKc)
RHINOWSO
10-01-12, 20:10
Thanks, nice set up. Although I doubt I'd need 40 MOA of slope to get to where I will end up shooting... :D
lifebreath
10-02-12, 00:19
Also, as I understand it the 20 MOA bases simply raise the height of the scope - or do they actually have a upward rise from back to front, although I'm pretty sure they don't.

Rhino

The 20 MOA (or any other value) mount cants the scope down in the front, so its a ramp running downhill from the rear to front. Same with the 20 MOA rail. This has the effect of angling the bore upwards so that you have 20 more (or whatever value) MOA of elevation adjustment. I have a 20 MOA and a 20 MOA mount. If you go that much, you need to make sure your scope can travel 40 MOA from the center (80+ MOA total travel). Otherwise, stick with 20 MOA.

My Hensoldt has over 100 MOA total travel (plus or minus 52 MOA or 15 Mils). With the 40 MOA of cant, I have about 93 MOA of adjustment from my zero. For out to 1000 yards, I don't need that much, in fact I could get by without ANY cant. However, many scopes don't have that much travel, and you need 20 MOA to gain what you need. I did it because the Hensoldt does not have a zero stop, and by using 40 MOA of cant, my 100 yard zero puts the scope about 2.5 mils (9.5 moa) from bottoming out. This means my turret will only turn about 1/4 turn past zero before stopping, creating a "pseudo zero stop."

For a precision bolt gun, I think you want a rock solid mount, which in my mind, precludes typical QD mounts. And there really is no need for QD on a bolt gun, since you don't have back up sights. One of the monolithic mounts is ideal in my mind, in that they are solid and easier to deal with than rings. You can still put it on a different rifle if desired almost as easily as a QD mount. I got a Near Mfg. Alphamount, but other good options exist.

Here's my rig:

http://www.lincolndiagnostics.com/public/doug/guns/FNSPR/spr1sm.jpg

http://www.lincolndiagnostics.com/public/doug/guns/FNSPR/spr2sm.jpg
RHINOWSO
10-02-12, 07:45
Ah, it all makes sense now that I picture it. Thanks again, very enlightening.
Canonshooter
10-13-12, 18:18
http://www.canonshooter.com/photos2/700-2.jpg

This is the Leupold Mark 4 (15 MOA) steel base, bedded to the receiver.

When I bedded the base, I decided to bond it to the receiver as per this technique (http://www.murphyprecision.com/Page/Scope_Base_Bedding) using Devcon Metal Filled epoxy. Because of the way the top of Remington 700 receivers are finished at the factory, I lost about half of the 15 MOA elevation doing it this way, but the the mount is rock solid and stress-free.

The first shot fired with this mount with the scope adjustments centered was about 7 inches high and about an inch to the left at 100 yards. The SWFA 10X42 HD scope has plenty of internal adjustment, enough for the .308 to go to 1000 yards with this set up.