Scope almost out of adjustment?

[jschroed]

I've mounted my Vortex PST on my Cooper using Talley Lightwieght one-piece rings. The problem is I only have about 20 moa left to dial up on the elevation turret. I'd like more.

Is there anything that can be done other than shimming the rear ring? I thought I red somewhere that Talley can machine them to improve this. I plan to call them tomorrow. Until then, any suggestions or experiences are welcome.

Thanks

 

[42769vette]

If you put a 20moa picatinny rail on it that will get you to 40moa of travel, if you can find a 30 moa rail that will get you to 50moa of travel

 

[westcliffe01]

A Viper PST is a 75MOA elevation scope. So if you put a "flat" base on it, you theoretically have 37.5 MOA in the "up" direction. If you use a 30MOA tilted rail on it, that would allow 37.5+30 = 67.5MOA of "up" travel. If you absolutely have to get the most travel possible out of the scope then that is what it would take.

The downside of course is that one is not looking through the center of the optical system at either close range or at maximum range, but on the other hand, this is what these scopes are designed for.

I'm a little curious how you only end up with 20MOA of travel after zeroing ? "Using" 17.5MOA to zero a scope indicates that something is wrong. Are you sure that you don't have a 20MOA rail and have it on backwards ? That way you "used" 3MOA to zero it after an initial 20MOA correction (the wrong way). I would check if it is possible that the rail could be reversed.

OK, checked what it is that you have and the base is integrated into the ring. Is the front and back ring the same ? Very little info on the Talley website, but they say nothing about the one piece rings being inclined.

 

[jschroed]

A Viper PST is a 75MOA elevation scope. So if you put a "flat" base on it, you theoretically have 37.5 MOA in the "up" direction. If you use a 30MOA tilted rail on it, that would allow 37.5+30 = 67.5MOA of "up" travel. If you absolutely have to get the most travel possible out of the scope then that is what it would take.

The downside of course is that one is not looking through the center of the optical system at either close range or at maximum range, but on the other hand, this is what these scopes are designed for.

I'm a little curious how you only end up with 20MOA of travel after zeroing ? "Using" 17.5MOA to zero a scope indicates that something is wrong. Are you sure that you don't have a 20MOA rail and have it on backwards ? That way you "used" 3MOA to zero it after an initial 20MOA correction (the wrong way). I would check if it is possible that the rail could be reversed.

OK, checked what it is that you have and the base is integrated into the ring. Is the front and back ring the same ? Very little info on the Talley website, but they say nothing about the one piece rings being inclined.

No rail on this installation. The Talley's I used are the base/ring combination. The screw spacing from the front to back are different, so a swap was out. I did contact Talley and they verified that I received the correct set of rings. They're sending me a new set out to try to see if that solves the problem. If it doesn't i guess that points to the optic, or possible the receiver. Kudos to Talley, great CS.

 

[westcliffe01]

Are you specifically trying to save every ounce of weight ? Using a one piece rail that is inclined at 20MOA and "conventional" rings gives you a lot more flexibility in setting up a scope. The only time I have used a 2 piece base is on my slug gun where ejecting a 20ga shell needs all the clearance it can get.

Most scopes I have set up have not needed more than 3MOA (12 clicks) of correction.

 

[jschroed]

I hear what you are saying in regards to weight and the amount you have dialed. The guys at Talley agreed that the scope should have more "dial up". I did consider a Ken Farrell rail. I'll see if the new rings make any difference.

I'll keep you posted and thanks to those of you with input.

 

[Engineering101]

You can get 20 MOA out of a set of Burrins signature Zee rings using the - 10 and +10 inserts under the scope front and back respectively. Graf's sells these for around $43. They come in three heights.

 

[bruce_ventura]

..Most scopes I have set up have not needed more than 3MOA (12 clicks) of correction.

That would be about right for a custom rifle with a trues action. However, I often find that factory rifles have the barrel installed crooked in the receiver, or the screw holes are drilled crooked Misalignment between the rings and bore of 8-20 moa are quite common.

This is likely the case with the OP's rifle.

 

[jschroed]

That would be about right for a custom rifle with a trues action. However, I often find that factory rifles have the barrel installed crooked in the receiver, or the screw holes are drilled crooked Misalignment between the rings and bore of 8-20 moa are quite common.

This is likely the case with the OP's rifle.

I would have hoped they would have noticed if the barrel was installed crooked or the mounting holes were drilled off center at the factory when they shot the test target. Anything is possible.

New rings are on the way and I sent the scope back to the manufacturer. Hopefully, when I assemble everything it will be fine.

 

[42769vette]

I would have hoped they would have noticed if the barrel was installed crooked or the mounting holes were drilled off center at the factory when they shot the test target. Anything is possible.

You might hope for to much. Factory rifles are mass produced, and it doesn't that much to get it out of square.

Custom rifles are built 1 at a time with ALOT more attention to detail.

 

[jschroed]

Well I received a new set of rings and I sent my scope in to have it checked. When the scope arrived I reinstalled the rings and scope and zeroed at 100 yards. With 100 yard zero I have 20 MOA available to dial up. Not as much as I'd like but it probably will work for my needs.

Thanks to those of you who replied.

 

[westcliffe01]

I just traded for a 308 Savage rifle on this forum. When I got the rifle and was checking it out, I found that the pin which locates the recoil lug had not been properly installed and was too long and too skinny and actually projected from the recoil lug on the barrel side. The end of the pin was sharp, as if it had been sheared and that sharp edge was sticking out like a cutting tool... When the barrel nut was torqued down, the projection of the pin gouged a shaving out of the nut and as the nut advanced the chip got bigger and bigger. It finally reached a point where the person torquing the nut thought it was tight, but in fact it had just locked up on the chip.

Later, when the rifle was fired, the forces acting on the barrel must have loosened it up slightly and although the nut could not rotate, the barrel could rotate inside the nut. This must have caused a bunch of problems (changing headspace, barrel harmonics etc etc).

If I recall, you do not have a Savage, but if this had been a Remington with a barrel shoulder, the pin could have gouged a chip out of the barrel shoulder instead and something very similar could have occurred. This was just a lesson to me in how things can go wrong in ways you really might not expect. I just today got my new NSS precision barrel nut and recoil lug which has a small cap screw instead of a pin, the head of the cap screw engaging in the groove in the reciever. It all fits very snug and of course the cap screw can't move axially and cause this problem... Now I'm just waiting for the "go" gauge to re-set the head space, then I will be all set.