Rifle Scopes 20 MOA rail; no effect

[Lumpybrass]

I'm in the process of setting up a Ruger RPR. The rail has 20 MOA built in at the factory.
After mounting Vortex rings and scope, I looked down the bore and compared it to the reticle and found both very close at 100 yds (within 3 inches).
I would have expected the need to crank in 20 MOA on the scope to zero it out.
I'm I missing something??

 

[ShtrRdy]

I would say continue on and zero the rifle/scope and then see how much up elevation adjustment you have.

 

[KZP]

It can be hard to tell until the rifle is shot.

 

[wade2big]

It can be hard to tell until the rifle is shot.

Its not just hard to tell, it is impossible to tell without pulling the trigger. OP, the 20moa is there.

 

[Racer88]

I'm in the process of setting up a Ruger RPR. The rail has 20 MOA built in at the factory.
After mounting Vortex rings and scope, I looked down the bore and compared it to the reticle and found both very close at 100 yds (within 3 inches).
I would have expected the need to crank in 20 MOA on the scope to zero it out.
I'm I missing something??

It seems you expected the scope to be zeroed merely upon mounting it? Or that it comes in the box zeroed / centered?

Maybe I'm not reading your post right. It seems that you think that if the rail was a 0-MOA rail, just mounting the scope (out of the box) would result in the bore and reticle being coincident at 100 yards. If that was your expectation, then... no. That's not how it works.

Accordingly, with a 20-MOA rail, zeroing your scope is not simply a matter of dialing 20 MOA on the elevation turret and calling that "zero."

 

[ck79au]

I'm in the process of setting up a Ruger RPR. The rail has 20 MOA built in at the factory.
After mounting Vortex rings and scope, I looked down the bore and compared it to the reticle and found both very close at 100 yds (within 3 inches).
I would have expected the need to crank in 20 MOA on the scope to zero it out.
I'm I missing something??

was the reticle centered in the elevation? shoot a 3 shot group and than you will know how much adjustment is needed to zero.

 

[Lumpybrass]

It seems you expected the scope to be zeroed merely upon mounting it? Or that it comes in the box zeroed / centered?

Maybe I'm not reading your post right. It seems that you think that if the rail was a 0-MOA rail, just mounting the scope (out of the box) would result in the bore and reticle being coincident at 100 yards. If that was your expectation, then... no. That's not how it works.

Accordingly, with a 20-MOA rail, zeroing your scope is not simply a matter of dialing 20 MOA on the elevation turret and calling that "zero."

was the reticle centered in the elevation? shoot a 3 shot group and than you will know how much adjustment is needed to zero.

I guess I did expect the scope to be in it's center of travel. I did shoot it, hence the 3" off zero.
I need to crank it to mechanical stop. If the full amount of travel is there, then the rail has contributed nothing.
Puzzling.

 

[Racer88]

I guess I did expect the scope to be in it's center of travel. I did shoot it, hence the 3" off zero.
I need to crank it to mechanical stop. If the full amount of travel is there, then the rail has contributed nothing.
Puzzling.

Even if the scope came out of the box, dead-center of travel vertically and horizontally... putting that on a 0-MOA rail (or any rail).... will NOT necessarily put the reticle zeroed to the bore or the POI at 100 yards. There's simply no way one could expect that. Every rifle is different. Scope mounts are different. Once the system is mounted and tightened, the only way it could all magically line up is just that... magic or luck.

You're going to have to zero the scope in any case. That means starting with a bore-sighting technique (easiest) to get on paper. Then make adjustments to make POA = POI. There are a few ways to go about it. Do a youtube search. Plenty of videos on that topic.

The 20-MOA rail simply gives you an additional 20-MOA of elevation range in the UP (farther away) direction. But, it happens at the expense of range in the DOWN (closer) direction. I think I'm saying that correctly. It takes away 20-MOA in the other direction. With most rifle set-ups, it works out, and we're still able to get a 100-yard zero. But, with the 20-MOA rail, you might not be able to get a 50-yard zero, for example.

WithOUT the 20-MOA rail, you might run out of vertical adjustment at the high end... say near 1,000 yards. So, the 20-MOA rail gives you more turret adjustment in that direction. But, again... takes it away in the other. The actual mechanical range of adjustment of the turret stays the same. The 20-MOA rail just cants the scope.

I hope that made sense! If not, someone will be along to explain it better than me!

 

[Lumpybrass]

Mounted the scope up and made only minor adjustment to zero out. Expected a need to crank 20 moa to zero.

 

[spife7980]

The difference in what you were expecting to see in your scopes shift from dead centered can be attributed to pretty much anything and everything. Its only 1/3 of a degree. Could be the action, could be the barrel, could be the barrel nut, the rings, the height over bore, the scope itself etc.

It has an effect. You still have 20 moa more than you would otherwise.


Also, just because it looks close looking down the bore doesnt mean that it will actually shot there. You have to actually zero the rifle by shooting to see where it is shooting. If you didnt then the need for zeroing the rifle would not exist.