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Old September 20, 2013, 03:01 AM   #1
David_S
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Join Date: February 11, 2008
Location: New Zealand
Posts: 149
Sako optilock ringmounts on new Sako 85 Finnlights way out vertically

I have a new Sako 85 Finnlight in 260 Rem. I fitted new 1" Low Sako Optilock Ringmounts (the one-piece base type) and temporarily mounted an old Leupold scope so I could work up a handload whilst I awaited a new Swarovski 4-12x50 (my first Swarovski).

When mounting the Leupold I noticed it required a considerable vertical adjustment to bring on target but I was not unduly concerned at the time as it was only temporary. The Swarovski turned up last week, so off came the Leupold and on went the new.

Well almost! When mounting a scope I like to have the vertical line close to the middle of the windage adjustment range and the horizontal line a little below the midrange so I can make full use of the vertical turret adjustment for longer ranges without straying too far from the midpoint. But when I bore-sighted the Swarovski at 25 yards the scope was more than 10" high. To bring this back to the centre would require 40MOA adjustment but there is only 43MOA total vertical adjustment in the scope!

What's going on here? A top quality Sako rifle with quality Sako mounts and a top quality scope should fit together better than this? I also have a new Sako 85Finnlight in 270WSM with a Zeiss scope and Optilock Ringmounts so I spent an afternoon mixing and matching between the two rifles. My conclusion was that there was nothing wrong with scope or mounts but the rear dovetail on the 260 was significantly lower than the front dovetail. It was also lower on the WSM but not as bad.

Has anybody else experienced this problem with the 85 Finnlights or other Sakos and if so what did you do about it? (I also have a Sako 75 Finnlight but have not yet checked it out as I would like to have at least one functioning Finnlight!)

The Optilock Ring Mounts are a solid compact quality mount and I particularly like the spherical inserts, but why is there no provision for vertical adjustment such as a range of off-centre inserts such as Burris use? Lateral adjustment is available by sliding the front mount on its tapered dovetail on the receiver which is a neat system.

As an experiment I tried placing traditional "beer can" shims between the bottom of the insert and the ring. It required 6 shims plus a layer of protective loom tape (approx 0.8mm total) to bring the rifle to a 200 yard zero. Not a permanent solution. The WSM required 3 shims + loom tape (0.5mm total).

There is no obvious place for permanent shims such as with the two-piece optilocks that I have on my Sako M995. I have tried putting shims under the mount on top of the dovetail and this looks as if it might work but I am concerned that this might not leave enough clamping surface for the mount. On the WSM it required 1.2mm shimming this way. (More than for shimming the insert as there is a gap between the mount and the dovetail to fill first).

My options
  1. Return rifles under warranty - wait months for a "solution" whilst I should be out hunting.
  2. Switch to 2 piece optilocks - extra cost and extra weight
  3. Switch to Burris or other rings - Sako ringmounts really don't match Sako rifles??
  4. Try the second shimming method above and hope the clamps hold - probably worth a try.
  5. Make some off-centre inserts - maybe the Burris ones will fit or can be modified? Anyone know?
  6. Any other suggestions??

My apologies for the long post, but thanks for reading this far and for any suggestions.

David
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Old September 20, 2013, 09:10 AM   #2
NWPilgrim
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Join Date: September 29, 2008
Location: Oregon
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Sako optilock ringmounts on new Sako 85 Finnlights way out vertically

I have a Sako A7, that came with the 2-piece Weaver bases. No problems with both being level or with sighting the scope.
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Old September 21, 2013, 03:06 AM   #3
David_S
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Join Date: February 11, 2008
Location: New Zealand
Posts: 149
A solution?

I think I may have found a workable solution. I abandoned the idea of shimming the base because of the potential loss of grip and experimented with an epoxy layer between the plastic insert and the bottom half of the ringmount.

I first coated the insert with car wax to act as a release agent, then placed some epoxy in the bottom of the ring and pressed the insert down on the epoxy squeezing it up the sides. After the epoxy set the insert was easily removed and left a near perfect bedding shaped to allow the insert to rotate as designed. It is a similar process to bedding an action. The only difficulty is in judging how far out to seat the insert as it is difficult to measure accurately. I just eyeballed it and came pretty close as my boresighting at 25 yards dropped from 10" high to 2". I might just leave it at that.

Below is a photo showing the .026" height difference between the rear and front dovetails which equates to around 17MOA which explains why I was so far off target.

I hope this helps others who have similar problems with Optilock ringmounts.

David

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