Is this 20 MOA Rail Backwards ?

Devlin

Devlin

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Hey Folks,

Sent the guys at ATRS an email on this but thought I would post here as someone in the forum here may know. I picked up a 20 MOA rail from ATRS seen in the pics below for a Tikka T3x CTR, I'm running ATRS rings on it with S&B PMII 5-25x56mm scope. The problem I am having is I am hitting about 20-22 inches high at 100 yards and I've hit the zero stop on the PMII and I think bottomed out the elevation.

I had bore sighted using the look through the barrel method and compare to scope/reticle and align the two at 25 yards.

What I am wondering is if I have the rail on backwards as it would appear to be possible to do so with the Tikka bolt pattern. Is there any way to tell for certain? Perhaps remove the rail and place a level on it and see which way the bubble sits?

IL4kSbH.jpg


16R5QZu.jpg


xeorTER.jpg
 
Remove the rail and measure the thickness. The rear should be thicker than the front.

I have a feeling it's zero stop issues. I had similar ones when first sighting in my first SB too (in my defense it was my second scope, and first one I zerod myself).

If your scope is in moa. Release the zero stop, dial up 24 moa then lock the zero stop, then dial down how much extra you dialed up.
 
reset your zero stop, chances are you forgot to screw it down all the way and the addition of a 20 moa base is causing you to be 20 moa high at the old zero stop location
 
The scope is MIL based, the S&B manual I have isn't really clear on how to reset the zero stop. Guess I'm off to do some more googling unless you folks can offer any guidance.

Measured rail and it appears to be mounted correctly, I measured on the gun as it's got blue loctite on the base screws and if I can avoid messing with that I will. Measuring with micrometer on flat surfaces the front portion is thinner than the rear so I suspect it is mounted correct now.

Found this advice in another forum which is what I think I will try next, and return to the range to confirm

<SNIP>
If you hit the zero stop and need to go lower you loosen the knob and turn it up and then retighten and dial down. So if you need to go 4 mils down and you hit 0 then loosen and turn the knob until you are on 5 mil mark to give some room to play and retighten and dial down the 4. After that just do above at 100 for your zero.
</SNIP>
 
Last edited:
Devlin said:
The scope is MIL based, the S&B manual I have isn't really clear on how to reset the zero stop. Guess I'm off to do some more googling unless you folks can offer any guidance.

Measured rail and it appears to be mounted correctly, I measured on the gun as it's got blue loctite on the base screws and if I can avoid messing with that I will. Measuring with micrometer on flat surfaces the front portion is thinner than the rear so I suspect it is mounted correct now.

Found this advice in another forum which is what I think I will try next, and return to the range to confirm

<SNIP>
If you hit the zero stop and need to go lower you loosen the knob and turn it up and then retighten and dial down. So if you need to go 4 mils down and you hit 0 then loosen and turn the knob until you are on 5 mil mark to give some room to play and retighten and dial down the 4. After that just do above at 100 for your zero.
</SNIP>
Click to expand...

yep do what the forum says. So reset your "zero" to +7 mil on your turret.Then turn turret to zero or how much you appear to be off. You should be able to use your reticle to "measure" how much your off. 20 moa is roughly 6 mil.
 
Ok just to be crystal clear on what I changed, I dialed up/increased elevation by +7mils with the set screws still screwed down so the reticle moved and clicked while turning it. I then loosened the set screws on the turret and reset the turret to the zero position (no clicking) when this was done.

With the turret now at zero I retightened the set screws on the turret so it now clicks again when turned.

Does this sound correct? Can't confirm till I hit the range again tommorow.
 
No you just added 7 mils of elevation ontop of the 6 it was already off. Do the reverse of what you did.
Then with the turret on zero, unscrew set screws, turn to +7 then tighten set screws and turn to zero (you want it to click this time).
 
bsand said:
No you just added 7 mils of elevation ontop of the 6 it was already off. Do the reverse of what you did.
Then with the turret on zero, unscrew set screws, turn to +7 then tighten set screws and turn to zero (you want it to click this time).
Click to expand...

Doh! Cheers thanks good thing I'm not flying space shuttles today! Think I've got it sorted now, essentially what I first tried above compounded the existing problem.

Range day tommorow planned to confirm everything. Many thanks for your help.
 
CGN to the rescue once again. The level of support and general (and specific) knowledge here is incredible and more than makes up for the few trouble makers who come on to cause problems. Phil.
 
Yup I'd agree Phil and the advice received was great and dead on accurate. I had indeed simply buggered up where I had the zero stop set. Once I made the correct changes all was well and working like a charm.
 
I have a 20 MoA rail on my t3, and looking at the side i can actually see that the back of the rail is higher than the front (muzzle) side.

OP did you figure out your rail? All your pics are top view so I can't tell.

Nevermind. I see that you did.
 
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