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That bald headed Geordie

Issues with offset rifle scopes?

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Hi Gents,

A few months ago now I found out I had an issue with my right dominant eye and had difficulty in focusing and went to the local eye clinic.

They said I had Posterior Vitreous Detachment which means the jelly substance becomes watering and sloppy (an age thing) but there was nothing they could do unless it gets worse and the retina becomes detached.  

Before I went to the eye clinic I was at a competition at Diggle and just couldn't get a good sight picture which spoilt my day.   So recently I was thinking how to resolve/improve this by maybe moving the scope over to the left by a few inches and use my left eye to get a decent picture and still shoot right handed (tried left handed shooting but cannot get away with it).

But after speaking with a local gunsmith today he said that a mechanical fix is easy to move the scope over,  but there might be an issue because the scope is now not in line with the barrel and although if zeroed at 100yds would it be possible to zero at 1000yds without any issue.

So before I move forwards does anyone have any thoughts on this or have known anyone who has used an offset scope like I want to do?

Any info appreciated.

Cheers

 

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I built a rifle a few years ago for a guy who had lost his right eye in an accident

He was right handed and wanted a right handed bolt gun 

The fix was to use a scalloped butt so he could use the rifle normally but look through the scope with his left eye 

I was sceptical that this would indeed be the solution but I’ve had numerous impressive target images and reports of killed deer following successful stalks 

Perhaps that may be a solution for you - providing you have flexibility in your neck to do this ?

 

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5 minutes ago, Ronin said:

I built a rifle a few years ago for a guy who had lost his right eye in an accident

He was right handed and wanted a right handed bolt gun 

The fix was to use a scalloped butt so he could use the rifle normally but look through the scope with his left eye 

I was sceptical that this would indeed be the solution but I’ve had numerous impressive target images and reports of killed deer following successful stalks 

Perhaps that may be a solution for you - providing you have flexibility in your neck to do this ?

 

Hi Ronin,

I did think of this and with the current configuration of the heavy gun I can do this without any aluminium being removed but my neck muscles can cope but it isn't comfortable lol.  But it would be a lot easier with say 2 inches taken away.   But unfortunately after chatting with the rifles maker he said that the comb is made up of 3 pieces and to remove the top section would make it too thin.    That thought was plan B but if Plan A (offset the scope) is not feasible because of zeroing issues then I might have to look at Plan B again.

Thanks for the quick reply

Les (in the Kingdom of the Blind,  the one eyed man is King lol).

 

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Hi Les

could you use the gun with some kind of prism or optical aid to allow you to look through that instead of directly through the occular?

If your using the gun for bench rest - is this single fixed distance - therefore the problem with convergence would be fixed with the sight offset on a set angle to align with point of aim / impact at that distance and allow windage ajust of the Scope within parameters 

 

Or 

 

have custom fabricated offset mount with horizontal vernier ajust to account for each distance shot -

again difficult to get repeatable and probably expensive - look at Ivey mount and tilt 90 degrees is what I had in my head ,,,,,

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Ronin.

Never thought of a prism or optical aid but yes if there is such a device that would fit a Nightforce scope then that seems a brilliant solution.  If you know of such a device then that would be interesting to check out for price/availability.

Yes the rifle is mainly used for either 600yd benchrest but mainly for 1000yd benchrest and if the above option is not achievable then offset the scope to a set angle to achieve poa/poi.   Not sure how the actual angle could be sorted as trigonometry stuff is not my thing lol

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I’ve seen simple devices that attach to scope to allow smartphone attachment not sure they are allowed in Comp though that may be the problem 

Sorry can’t think of brand name 

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A long established problem, but for other reasons

The WW2 Garand sniper rifle could only be clip loaded from the top, so a scope was offset on the left of the receiver and a special cheekrest made to push the cheekweld over by the same amount to allow the eye to be inline with the scope - there had been a few similar scopes set up this way in WW1 as well to allow stripper clip feeding.

Early gun designs before regular/obligatory scope usage became a thing were commonly top eject. To allow scope use on this type of gun, some firms had side mounts to allow scope fitting without interference with the cartridge ejection.
The main firm that did make these mounts was Weaver - they are still available

As to convergence - the scope is offset to the bore by maybe an inch or so - but parallel. I'd say for the average shooter you'd be pushed to tell the difference on target once the scope is zero'd on paper -  but maybe if a modern scope is used notes could be made for the correct windage mark for each distance?

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I think (having thought about this overnight) the angular differences would be so small betteeen the bore line and scope to target (at one distance ) there would be little or no loss windage at 600 or 1000 yd’s 

However - there would be some adjustment required for line of sight/ bore line to target at the alternate distance - again I think this may be very small (possibly as little as a MIL  / MOA )and within the scopes adjustment as you’re looking at straight line convergence rather than a trajectory of bullet plotted pathway  

Simple (non mathematical) test would be bore sight at 600 place cross hair on target then bore sight at 1000 and see if any difference in relationship of cross hair and bore sighted target - I’ll hazard a guess it won’t be much discernible difference to the human eye

 

That would be a very rough test   

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Sorry to hear of your problem Les.

I've just put an AK47 together for myself, and one of the first things I tried was a side mounted Dragunov scope, which isn't in line with the bore.

Apart from the total lack of cheek weld, it works perfectly, at 100 yards anyway.

There will be some left/right movement I would think, at greater ranges, but any modern scope will have ample adjustment .

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Ive had PVD's in both eyes,  one caused a detached retina in my left eye. 

In my case the sight return to normal pretty quickly....( till the cateracts came along 🙂 )

PS:  Dont fret about the Cateracts mine were certainly helped along by a history of having to take Maxidex for chronic Iritis.

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Why not just use a FFP scope and ‘in close’ use a different horizontal cross hair for zero to allow for the offset and when you get out to 600 plus then use the regular central cross.

just saying this might be simpler?

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2 hours ago, Dellboy said:

Cheers Dellboy,  just had a look and yes they are cheap Chinese offerings but have ordered 2 a few moments ago and will test the theory of the scope being to one side.  After reading various replies on here and also on 6BR it seems that most shooters say that it didn't seem to make much difference referring to divergence of point of aim and point of impact as the scopes windage should take care of that.   

So thanks to all that have given me their views and solutions which is much appreciated.

Les 

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4 hours ago, baldie said:

Sorry to hear of your problem Les.

I've just put an AK47 together for myself, and one of the first things I tried was a side mounted Dragunov scope, which isn't in line with the bore.

Apart from the total lack of cheek weld, it works perfectly, at 100 yards anyway.

There will be some left/right movement I would think, at greater ranges, but any modern scope will have ample adjustment .

Thanks Baldie for your comment in the last paragraph which reflects other shooters comments from in the States.   So as long as I have enough windage on my scope to get poa/poi converging I will be good to go.

ATB

Les

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5 hours ago, Ronin said:

I think (having thought about this overnight) the angular differences would be so small betteeen the bore line and scope to target (at one distance ) there would be little or no loss windage at 600 or 1000 yd’s 

However - there would be some adjustment required for line of sight/ bore line to target at the alternate distance - again I think this may be very small (possibly as little as a MIL  / MOA )and within the scopes adjustment as you’re looking at straight line convergence rather than a trajectory of bullet plotted pathway  

Simple (non mathematical) test would be bore sight at 600 place cross hair on target then bore sight at 1000 and see if any difference in relationship of cross hair and bore sighted target - I’ll hazard a guess it won’t be much discernible difference to the human eye

 

That would be a very rough test   

If the scope is offset to the left of the rifle by, say,  2" and adjusted to 'zero' at 100yds won't POI be 2" to the right at 200yds, 4" at 300 etc?

If 'zeroed' at 600 then at 1000 POI would be 1.5" right

Would it not be better to just allow a 2" offset aiming point and then set up the scope parallel to the rifle bore.  Always 2" left at all distances.

Of course, knowing the increasing offset with distance you could just allow for that in the windage.  A dope chart would be useful (I would be happy to oblige if my geometry is upto it!)

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Happy to help Les 

 

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57 minutes ago, Popsbengo said:

If the scope is offset to the left of the rifle by, say,  2" and adjusted to 'zero' at 100yds won't POI be 2" to the right at 200yds, 4" at 300 etc?

If 'zeroed' at 600 then at 1000 POI would be 1.5" right

Would it not be better to just allow a 2" offset aiming point and then set up the scope parallel to the rifle bore.  Always 2" left at all distances.

Of course, knowing the increasing offset with distance you could just allow for that in the windage.  A dope chart would be useful (I would be happy to oblige if my geometry is upto it!)

Thanks for the info and when I get the offset mounts from 'Corona-land' will disinfect them first and mount them to see how far left the centreline of the scope is in relation to the bores centreline.

Hopefully a local indoor range might be opening soon (ish) subject to confirmation and will do a 100yd zero and see how much left / right windage I have available.  

After your kind offer then if I zero at 100 yards and it impacts exactly at the point of aim,  then how far would my bullet impact right at 1000 yards?   If it is only a few minutes worth then that is nothing to worry about as my scope has 40 minutes worth of windage and is pretty much already in the middle of the range in a non wind situation.

The plot (like my gravy) thickens!!!

Cheers,

Les

 

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1 hour ago, That bald headed Geordie said:

Thanks for the info and when I get the offset mounts from 'Corona-land' will disinfect them first and mount them to see how far left the centreline of the scope is in relation to the bores centreline.

Hopefully a local indoor range might be opening soon (ish) subject to confirmation and will do a 100yd zero and see how much left / right windage I have available.  

After your kind offer then if I zero at 100 yards and it impacts exactly at the point of aim,  then how far would my bullet impact right at 1000 yards?   If it is only a few minutes worth then that is nothing to worry about as my scope has 40 minutes worth of windage and is pretty much already in the middle of the range in a non wind situation.

The plot (like my gravy) thickens!!!

Cheers,

Les

 

Hi Les

It will depend on the offset of the scope's centre line from the centre line of the bore.

For the moment, if we assume the scope is 2" left and we set the scope to hit a point exactly 2" left of the centre of the aiming point (the dead centre of the target); then that will prove the scope is parallel to the bore - that's our starting point so we need to record the turret windage setting.  Next adjust the scope from that setting so the POI is dead centre - that's a 100yd zero.  Record the windage setting.  That's the angle required for convergence at 100yds.   It should be close to "Right  2 moa".  This is the maximum you will need as all distances further away will require less angle to compensate for the 2" offset

So, if you were setting the scope parallel to the bore it would still be 2" offset at 1000yds but now we only need to adjust the smaller angle of 2" @ 1000yds which is only 1/5th of an moa.  At 800 yds it will be 1/4 moa - 1 click on most moa scopes.  This is what I think Ronin was suggesting.

You will have no problem at all, just dial in the small offset, make that your 'mental zero' and adjust any required windage settings from there (all offsets are Right Windage for a left offset scope).

  • 100 = 2moa
  • 200 = 1 moa
  • 300 = 2/3 moa
  • 400 = 1/2 moa
  • 500 = 2/5 moa
  • 600 = 1/3 moa
  • 700 = 2/7 moa
  • 800 = 1/4 moa
  • 900 = 2/9 moa
  • 1000 = 1/5 moa

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4 hours ago, Popsbengo said:

Hi Les

It will depend on the offset of the scope's centre line from the centre line of the bore.

For the moment, if we assume the scope is 2" left and we set the scope to hit a point exactly 2" left of the centre of the aiming point (the dead centre of the target); then that will prove the scope is parallel to the bore - that's our starting point so we need to record the turret windage setting.  Next adjust the scope from that setting so the POI is dead centre - that's a 100yd zero.  Record the windage setting.  That's the angle required for convergence at 100yds.   It should be close to "Right  2 moa".  This is the maximum you will need as all distances further away will require less angle to compensate for the 2" offset

So, if you were setting the scope parallel to the bore it would still be 2" offset at 1000yds but now we only need to adjust the smaller angle of 2" @ 1000yds which is only 1/5th of an moa.  At 800 yds it will be 1/4 moa - 1 click on most moa scopes.  This is what I think Ronin was suggesting.

You will have no problem at all, just dial in the small offset, make that your 'mental zero' and adjust any required windage settings from there (all offsets are Right Windage for a left offset scope).

  • 100 = 2moa
  • 200 = 1 moa
  • 300 = 2/3 moa
  • 400 = 1/2 moa
  • 500 = 2/5 moa
  • 600 = 1/3 moa
  • 700 = 2/7 moa
  • 800 = 1/4 moa
  • 900 = 2/9 moa
  • 1000 = 1/5 moa

Cheers bonny lad for that information,  very useful and even a Geordie can make sense of that lol.

Once I get the Chinese knock off offset mounts I will see how much the scope centreline is to the left of the bore centreline and take it from there.

Les

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3 minutes ago, That bald headed Geordie said:

Cheers bonny lad for that information,  very useful and even a Geordie can make sense of that lol.

Once I get the Chinese knock off offset mounts I will see how much the scope centreline is to the left of the bore centreline and take it from there.

Les

best of luck mate, always happy to help if I can

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On 5/14/2020 at 6:02 PM, saddler said:

A long established problem, but for other reasons

The WW2 Garand sniper rifle could only be clip loaded from the top, so a scope was offset on the left of the receiver and a special cheekrest made to push the cheekweld over by the same amount to allow the eye to be inline with the scope - there had been a few similar scopes set up this way in WW1 as well to allow stripper clip feeding.

Early gun designs before regular/obligatory scope usage became a thing were commonly top eject. To allow scope use on this type of gun, some firms had side mounts to allow scope fitting without interference with the cartridge ejection.
The main firm that did make these mounts was Weaver - they are still available

As to convergence - the scope is offset to the bore by maybe an inch or so - but parallel. I'd say for the average shooter you'd be pushed to tell the difference on target once the scope is zero'd on paper -  but maybe if a modern scope is used notes could be made for the correct windage mark for each distance?

The M1C or M1D from reading were decent sniper systems to 600 yards or so but not comfortable to use. I don't own one sadly and never shot one. The offset was a factor in accuracy and I would think a huge factor in finally looking for a replacement. Not sure exactly when the USA Armed Forces decided to go with non walnut stocks in sniper rifles perhaps after the 70''s?

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