Optics Install Dilemma-10MOA missing

[PatC415]

Today I installed a Vortex 6-24-50 PST MOA on my Ruger Precision Rifle 6.5c.
The RPR has a 20MOA rail, the rings are Vortex 1.25's with "zero" cant.
The Optic has 65MOA of up and down, divided by 2(half), or 32.5MOA.

I should have 32.5 MOA, which is half, plus another 20 from the rail, for a total of 52.5MOA elevation.

I ended up on the second rotation up, with a total of 42MOA left over...???
Very Puzzled...where did 10MOA go???

Just so you know, I have the exact same optic on my 308 flat rail with a 20moa mount, and have slightly more than 52MOA left over.

Any ideas from the wise Calguns Crowd here on Christmas Eve?

Merry Christmas everyone!

[Mute]

Couple of things. Is your windage centered and do you have more than 32.5 available going the other direction?

[penguin0123]

Not every scope zeroes at the half way point. And even then, it depends on what range you zero at. For example, if you zero at 25yds, expect to have less "up" clicks than a 100yd zero.

If it really bothers you, buy a 20MOA cant mount to get more "up". 35-ish MOA should get you to 1kyd, so I'm not sure that is necessary.

[CouchOperator]

It could be the rifle itself. Ruger isnt exactly known for precision machining/tolerances

[PatC415]

Couple of things. Is your windage centered and do you have more than 32.5 available going the other direction?

Yes, centered windage, a few clicks difference left/right

Not every scope zeroes at the half way point. And even then, it depends on what range you zero at. For example, if you zero at 25yds, expect to have less "up" clicks than a 100yd zero.

If it really bothers you, buy a 20MOA cant mount to get more "up". 35-ish MOA should get you to 1kyd, so I'm not sure that is necessary.

Zero'd @ 100, just like my 308.
I'm shooting regularly out to 1K, and only needed 30moa, but I'm out of elevation @ 1200, which is what I was going to shoot this week. I should really have enough elevation with this combo to go out to 1400.

It could be the rifle itself. Ruger isnt exactly known for precision machining/tolerances

That may be the case. I might swap out scopes and see if it's the optic or the rifle.
Thanks guys for the replies.

[CouchOperator]

No worries. Do please consider that adding a canted base will not change the amount of adjustment inside the scope. The internal adjustment distance reimains constant. It only changes its relation to the bore from zero. I know a couple dudes that run 30 or 40 MOA bases on AI's for this reason.

[penguin0123]

Zero'd @ 100, just like my 308.
I'm shooting regularly out to 1K, and only needed 30moa, but I'm out of elevation @ 1200, which is what I was going to shoot this week. I should really have enough elevation with this combo to go out to 1400.

Sounds like getting a 20/30/40MOA cant mount is in your future. Effectively, you're moving your zero down lower in the turret travel with the canted mount. Just know that optical quality is never the best at either extremes of the turret travel.

[PatC415]

So here's an update:

I swapped scopes, switched around rings, remounted and re-zeroed with the same result. This RPR with it's 20MOA rail, is only giving me 8MOA zeroed @ 100yds. I'm getting roughly 40 MOA out of both scopes. I should be getting 52MOA total. So the RIFLE, is out 12MOA.
My barrel is either shaped like a banana pointing toward the ground, the barrel is not mounted square to the receiver, or the top of the receiver and rail are not 20MOA To the POI of the barrel.
12MOA seems like a rather large discrepancy in machining for a "precision rifle."
I'll gonna try a 20MOA mount and see where that gets me. Maybe even contact Ruger and see what they have to say.

[HK Dave]

Please keep us updated. Actually pretty curious how this pans out.