Sightron S-TAC problem, need help here

[bikemutt]

I bought a brand new S-TAC 4-20x50 which I mounted on a Cooper 21 300BLK rifle, Warne two-piece base with Leupold 30mm rings.

On sight-in with factory ammo I could only get 1" left of the bullseye when I ran out of scope adjustment, at 25 yards. Packed it up and shot a different rifle.

Back home I used my laser bore sighting tool and confirmed; there is no way to get the green dot to align with the crosshair, it's left of it.

I removed the scope and mounted a different scope I pulled from an AR15 upper; no problem aligning the crosshair with the bore sight green dot, plenty of room either way. And that's from the scope's center of windage adjustment range.

Then I mounted a red dot to the front base, no problem aligning to bore sight. Moved the red dot to the rear base, no problem.

At this point I have to believe the scope is defective. I'm a Sightron fanboy but they all let a turd fly from time to time.

Am I overlooking something here? Anything more I should try before I make a warranty claim?

Thanks team THR!

 

[LoonWulf]

Nope, u have a scope issue, and yes they do happen. I wouldn't let it put me off the brand unless they handle the replacement request poorly.

 

[Walkalong]

Adjustable rear base?

 

[bikemutt]

Adjustable rear base?

Yup. I called Sightron this morning and spoke with a tech. He pointed out to me the reason why the AR scope lined up is because it's much lower magnification allows for more windage adjustment.

This rifle originally had Leupold bases with the ability to adjust the rear ring's windage, I'd replaced these with Warne Weaver-style bases because they look nicer to me.

So, it's back to the Leupold bases, accuracy trumps looks every day and twice on Monday

 

[Walkalong]

I have the same scope. Picked it up the last time Midway put it on sale.

I am going to put it on a .222 Mag, replacing a Vortex Viper. I meant to do it last week, but forgot to bring it to the range with me along with the rifle, bags, and rest. *Sigh*

 

[LoonWulf]

Interesting, I'm surprised there was that much difference between scopes adjustment ranges. Guess it's not something I've run into yet.
Glad you got the info to get it working!

 

[bikemutt]

It really makes me wonder why Leupold came up with the windage adjustment scheme. If an action is tapped dead on, the base is dead on, and a scope is dead on with 0 windage adjustment, they should line up prefect. If it all worked this way scopes probably wouldn't need windage adjustments other than for wind.

I suppose it's possible that if a particular action is off by a hair, a base is off by a hair, and a scope if off by a hair, and if all the hairs are in the same direction, you need a Leupold base.

I just wish I still had all my hair

 

[Walkalong]

I suppose it's possible that if a particular action is off by a hair,

More than possible, been known to happen. Most are fine, but not all.

Center the scope, then use the adjustable base to get as close as possible windage wise before using the scopes internal adjustment.

 

[Gordon]

Or use a set of Warne Maxi rings on the Warne bases. I took almost all opposing screw rings systems off years ago and have not had a problem since Redfield cost me a trophy elk