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Scope issue on my Thomas FT rifle. I have my Sightron 10-50X60

June 29 2017 at 4:47 PM
Don Armstrong  (Login doninva1)
YF12

scope setup for clicking. At 10 yards, I'm hitting dead on. At 55 yards, I have to hold to the left or click 4 clicks to the right. Which way do I need to rotate my scope, when looking thru it, to line up my horizontal. Thanks, Don

 
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Scott Hull
(Login Scotchmo1957)
YF

Re: Scope issue on my Thomas FT rifle. I have my Sightron 10-50X60

June 29 2017, 6:15 PM 

Not enough info to diagnose the problem. Set your zero to your apex distance, and then shoot at 10 yards and 55 yards. Does the 10 yard hit right or left? Does the 55 yard hit right or left? The following diagram might be useful:

CANT-00.JPG


    
This message has been edited by Scotchmo1957 on Jun 29, 2017 6:16 PM


 
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Joe Mags
(Login Joemagjr)
YF12

Excellent Diagram. Thank you Scott! nt

July 4 2017, 6:11 AM 


 
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JimC
(Login 22Jim)
YF

4 Clicks on your scope at 10 yards results in ....

June 29 2017, 6:44 PM 

a pellet movement of .05 inches, barely perceptible. Your scope has 1/8 MOA per click adjustment or 8 clicks = 1 inch at 100 yds or .10 inches at 10 yds. I would set it to be dead on the 55 yd target and forget everything else.

Scott's point about cant is also very applicable. Also have you trued your scope rings?

https://www.midwayusa.com/product/2130187492/wheeler-engineering-scope-ring-alignment-and-lapping-kit

Jim in Sacramento


    
This message has been edited by 22Jim on Jun 29, 2017 6:45 PM


 
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Scott Hull
(Login Scotchmo1957)
YF

0.050" is half the wiggle room

June 29 2017, 6:59 PM 

for a 3/8" target at 10 yards. If you can hold/shoot 1moa every time, you'll still make those shots. If your spread is 2moa, you can't spare those clicks.

 
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JimC
(Login 22Jim)
YF

My math may not be 100%

June 29 2017, 7:20 PM 


but I think .05in is 1/4 of he wiggle room. 0.375 - 0.177 = .0198 / .05 is approx = 4 or 25%.

0.198 = 2 MOA at 10 yds, .05 = 1/2 MOA.

Jim in Sacramento

 
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Scott Hull
(Login Scotchmo1957)
YF

You'd be right if it were a random error.

June 29 2017, 8:54 PM 

But it is not a random error.

The error is 4 clicks to one side only. The unidirectional wiggle room is 0.099".

0.099 / .05 is approx = 2 or 50%

wiggle-room-00.jpg

 
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Don Armstrong
(Login doninva1)
YF12

Jim, I use the Burris signature zee rings, with the inserts. The

June 29 2017, 8:26 PM 

Thomas will be within a inch at 30 yards with your scope at optical center. Have tried a Sightron, Leupold comp. and a Nikko MK11 10-50X60. Didn't believe it till I tried it. Don

 
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Don Armstrong
(Login doninva1)
YF12

Thanks for the help guys, I think I got it. I put a level on the gun and

June 29 2017, 8:07 PM 

scope. It was off a little. I just shot 30 targets on my FT range and it seems to be better. Originally I was hitting the 10 yard shots but hitting right at 55 yards if holding center. If I clicked right 4 clicks, I was hitting at 55 but splitting my 10 yard 3/8" target.

 
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Scott Hull
(Login Scotchmo1957)
YF

Re: Thanks for the help guys, I think I got it. I put a level on the gun and

June 29 2017, 9:37 PM 

Checking just the 10yd and 55yd poi is insufficient to diagnose a cant problem. Zero at the apex and then check your 10 yard and 55 yard windage.

If the three points (10yd, apex, 55yd) are in a perfect line, you have only a scope cant problem. You will need to rotate the scope in the mounts. If the three points are not in a line, you definitely have a gun cant problem (and you might still have a scope cant problem). First order of business when shooting multiple distances with significant rise and drop, is fix any scope cant problem. Scope cant cannot be fixed with a bubble level. Once you fix the scope cant, you can use a bubble level while shooting in the field to correct for any gun cant.

CANT-03.jpg

 
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Don Armstrong
(Login doninva1)
YF12

Thanks Scott, I will do that tomorrow. Don NT

June 29 2017, 10:24 PM 


 
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Bill Day
(Login dayjd2)
YF12

Don you have received some Great advice ............

June 29 2017, 10:03 PM 

A very unnoticeable wind drift won't make any difference at 10 yards but at 55 yards 1" to 1 1/2" is possible from my experience. Glad to hear you have the problem under control.

 
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Will Piatt
(Login saddlemountaingunsmith)
YF

Great info guys, thanks

June 30 2017, 8:04 AM 

Don, Zee rings definitely the way to go. Use this tool to align the scope over the bore while the gun is in a vise. Then use a plumb bob to level the cross hair. It will get you real close real quick.

http://www.brownells.com/gunsmith-tools-supplies/sight-scope-installation-tools/scope-reticle-levelers/vertical-reticle-instrument-prod6097.aspx


    
This message has been edited by saddlemountaingunsmith on Jun 30, 2017 8:12 AM


 
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DonC
(Login DonC)
YF

Yes Will.....

June 30 2017, 6:10 PM 

That is how I do it. Works perfect. The tool is worth every cent.
I also love Burris insert adjustable rings. Be sure and order a set of 20 inserts (optional) in case of severe droop.


    
This message has been edited by DonC on Jun 30, 2017 6:11 PM


 
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dan_house
(Login dan_house)
YC

So I can expand my definition of "cant"

June 30 2017, 11:30 AM 

by saying if the reticle is not "square" to the bore and and or not "level" its canted?

now youve got me thinking I need to recheck my scopes....

SO whats the remedy if I have a scope that level, but not aligned over the bore? Shim? Lap the rings?

yea, now Im gonna have to check all the guns......


 
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Paul Porch
(Login paulporch)
YF12

Dan, Sportsmatch fully adjustable rings. Covers elev and windage. About $70 on Amazon

June 30 2017, 2:05 PM 


 
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Don Armstrong
(Login doninva1)
YF12

Paul, that's a great price for fully adjustable Sportsmatch rings

June 30 2017, 2:25 PM 

I paid 144.00 for fully adjustable mounts. Have gotten the elevation only adjustable Sportsmatch for 60.00. Don

 
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Scott Hull
(Login Scotchmo1957)
YF

Re: So I can expand my definition of &quot;cant&quot;

June 30 2017, 5:49 PM 

Shims? Adjustable mounts?Lapping? None of those will correct cant problems.

Scope cant is fixed by rotating the scope in the rings. Gun cant is avoided by holding the reticle level when shooting.

 
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Paul Porch
(Login paulporch)
YF12

Scott, agreed for scope cant. I was suggesting the adjustable rings to

June 30 2017, 7:05 PM 

Dan,not Don, as Dan indicating the scope being not aligned with his barrel. I had this with my Steyr that the chassis is flexed because of the weak spot on the rt side where the lever is positioned.

Fully adjustables corrected the issue for me. Now that I put a rigid Mateos rail on the gun, it firmed up the flex, and the adjustable rings were not necessary. Before, the 10 yard was left after zeroing at 30 and the 55 was right. There, the scope was forced out of alignment.

Sorry if I confused the original issue...

 
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Scott Hull
(Login Scotchmo1957)
YF

Solution does not require adjustable rings.

June 30 2017, 8:32 PM 

"...Before, the 10 yard was left after zeroing at 30 and the 55 was right. There, the scope was forced out of alignment..."

Scope Cant: CCW
Gun Cant: CW

Paul, you can fix that by rotating the scope in the rings and then holding the reticle level. The only time you really need adjustable mounts is when you don't have sufficient turret adjustment remaining.

 
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