Rifle Scopes Question on Scope Elevation Adjustiability

[map_it]

The platform is a DPMS AR-10 with a flattop rail on it. I placed a Larue SPR-S which is the cantilever mount to has 10 MOA of cant built in to the mount. I did this because my barell is only 16.25 inches and I loose about 200 fps out of the muzzle so I thought the additional canted base would be nice for longer shots. I place a Swarvoski 3x9-36 Scope Z3 AV 1" tube Scope on the weapon. When I bore sighted the rifle it appeared I ran out of adjustment?

The bore sighter I used was the Leupold Zero Point. If I understand the way to use it I beleive you measure the distance from the CL of the optic to the CL of the bore. This was 2.5 inches. So I placed the bore sighter at 2.5 inches and adjust me reticle to match the inside target on the grid.

Have I missed something or does the Swarvoski with a 1" tube having 58" or total elevation travel which is only 34" of useable travel not enough to correct its self with the 1.5" mount above the rail having the additioanl 10 MOA cant. I hope I just do not understand how to use the Boresighter.....

Please Help.....(I'm a Newbie...)

 

[redbullitt]

Re: Question on Scope Elevation Adjustiability

I would not think a 10 minute base would be a problem for any scope, let alone a good quality one.

The scope being 1.5 inches over the bore is pretty standard stuff and should not be an issue at all. The scope should be mounted straight, not canted, and not even notice that it is 1.5 inches above the bore. Its only when you slant the scope, like with your base, that it would be changing.

Have you actually fired the rifle? Hopefully there is just an issue with the bore sight.

If I were you, I would first fire the rifle. Hopefully you will be good to go. BUT if not, I would take the mount and scope down off the gun, check and reassemble and check again to make sure everything is ok. Maybe you have an assembly glitch. If there is still trouble, try installing the scope on the rifle with different mounts, maybe from another stick that is proven. Maybe the mount is questionable. Worst case scenario, mount the scope on a proven weapon/mounting combo and see if the trouble is in the scope or the rifle.

good luck

 

[map_it]

Re: Question on Scope Elevation Adjustiability

No I'm planning on firing the rifle later tonight thanks for the options. I will repost my results.

I think the bore sighter was not made for my application......

 

[One-Eyed Jack]

Re: Question on Scope Elevation Adjustiability

You don't need a boresighter, you can simply look through the barrel at a target, even with an AR, and zero the scope about 5 inches below the same point at 100 yards. You will have to remove the BCG to look down the barrel, and taking off the lower will help you position the upper on a shooting bag or other support. Then, reassemble and fire your gun for a precise zero adjustment.

If your scope has 58" of total elevation travel at 100 yards (or about 55 MOA), with half up and half down from optical center, then you have 27.5 MOA up and down. With a 100-yard zero you lose 5 MOA, but the scope mount will add 10 MOA.

Altogether you should have about 32 MOA of useable up elevation and have no problem with zeroing at 100 yards with your setup.

 

[maladat]

Re: Question on Scope Elevation Adjustiability

I bet you just didn't get the height on the boresighter set quite right. A small error will totally screw your boresight process.

 

[map_it]

Re: Question on Scope Elevation Adjustiability

One-Eye-Jack your awesome. I did this an all was good. I went to an indoor pistol range and got it shooting at 0.75 inchs low at 25 yards.

I'm going to be on a 200 yards range tomorrow to fine tune. But your trick did it. I think I'll have plenty of adjustment and eventhough it is not a true Tactical scope man the Swarvoski Glass is better than I've ever had....

Can't wait to get my Tactical .308 Bolt Gun build competed later this year and step into a real scope say a S&B or Premier.....