Piccatinney Mounts

Ok, someone inform this old goat what the 0, 10,20 MOA means when talking about the rails used on LR guns. What are the pluses & minuses? Thanks

0 MOA will, theoretically zero then scope in the middle of its' elevation travel.

10 MOA will zero the scope and give you an additional 10 MOA elevation travel on the top end.

20 MOA will zero the scope and you an additional 20 MOA elevation travel on the top end.

This is for dialing elevation for long range shots. Without a 20 MOA base you can run out of elevation travel for a long range shot. 20 MOA equates to about 6 Mils. So let's say you were shooting a 308 to 1000 yards, and you need 10.0 Mils. You have the scope mounted on a 0 MOA base, and you run out of travel at 8 Mils. You have to hold the other 2.0. Had you mounted the scope on a 20 MOA base you would not have ran out of travel for the distant shot. Most long range scopes are designed to be mounted on a 20 MOA base.

One day I would like to build a big rifle for 2000 yards. I will mount the scope on a 40 MOA base to have enough elevation travel to get me to 2000 yards. The downside, that could happen, is that at 100 yards I dial the elevation POI down as far as it will go, but I am still impacting higher than I want to be. I ran out of travel on the low end, in that case.

Also, make sure your scope has enough internal travel to accommodate a canted base. Some scopes do not have enough internal travel and with a 20 moa base, they can not zero their rifle. If there is a certain scope you want to make sure you have enough, just ask. I say this because I have seen shooters get a high magnification scope on a 1" tube and install a 20 moa base, and there not be enough down adjustment to get a zero.

If you are not shooting longer than 500 yards you do not need a canted base

Thanks Guys, I thought that was the case but was not positive. Daniel

Just remember

MOA and BDC Turrets are your friends

Are you saying that you can buy a base with different MOA? Sorry if this is a foolish question.

Yes, a 20MOA base buys you an additional 20MOA of elevation. Your actually just "borroing" it from your scopes down elevation. In theory,with a 20MOA base the scopes new "zero" is minus 20MOA, so you have an additional 20MOA availabe in "up" elevation, and 20MOA less "down" elevation available. It's important to know what the scopes available internal adjustment is before playing with elevated bases.

So you need to match a given scope with the proper base. My brother has a Nikon on a rifle that we tried to sight in and failed to do so. The scope had turrets with numbers on the bottom of turret as well as caps on top of the turret with adjustments there. We were doing something wrong or did not have the right match of scope and base, we never got it right.

What could you not get right?

Was the rifle consistently high, low, or all over the place?

We never got it sighted in....as well as I remember most of the time it was high. The more we tried to sight in the more we were all over the target. Obviously we were not doing something right in our effort to sight at 100 yards.

So it wouldn't group anywhere?

No we did not get a group....I would almost think the scope was defective except for the scope being different from what I am use to. As mentioned earlier the turrets had a setting on the bottom that was numbered as well as having a cap on top that would come off and settings could be changed there. The setting for elevation was on 2 I think and we used the adjustment on top (under the cap) to adjust up or down. The scope I am used to do not have the setting on bottom of turret.

Had to return a new Vortex Viper HD last year that would not sight in, shooting at 50 yards groups were about 8 inches without touching the turrets, That was on a rifle with low recoil and had shot sub MOA the day before with a different scope and rings. Went home pulled a scope from another rifle and mounted it on in the same rings and was back to sub MOA. Returned it to Vortex and got another that is still in the box.

Wilhunt, a picture or model of the scope might help solve the problem. It could be a bum scope, but maybe not. It sounds like what you're describing as the numbers under the turret might be revolution markers. Some scopes with finger adjustable turrets have a second set of markers/numbers under the turret itself to help keep track of how many revolutions you've turned while adjusting your scope. Then, typically once you're zeroed, you loosen an Allen screw on the turret itself to set it to "zero". If your scope is like this, and you were on two of your revolution marker, this could be the issue. Also double check your mounting hardware and confirm everything is locked down tight.

^^This, exactly^^

Thanks so much for the information, what you have said does make sense. I don't have the scope but will try to get one. If it was set on 2, new out of box, and we tried to sight it in using the top finger adjustment shouldn't that work?

Also check details on scope. Make sure you understand the difference between MIL and MOA. I had a scope going wildly on adjustments until I figured out turrets were MIL and not MOA. Pilot error.

Adding...if getting a canted MOA base, make sure you have the thinner part to the front. Don't get your base backwards.

Best thing to do is bore sight it, then shoot the rifle at 100 yard paper. Dial the point of impact to match point of aim. All the while completely ignoring what revolution your turret is on, as well as what number the turret is reading. Once the bullets are hitting center on the target, loosen the turret screws, rotate the turret to "0", tighten the screws, note what revolution the turret ended up. Rifle and scope will be zeroed