Can anyone explain the logic behind Sako's tapered integral scope ring mount design? It seems incre

[bossmustangace]

Ok, I'll state my piece and then take cover......

I find the Sako design for their scope mounts to be problematic. To be perfectly clear, I'm referring to the tapered area of the receiver upon which you mount the scope rings to be considered the "mount".


Why is the aft mount area so much more narrow than the corresponding forward one? What purpose does this serve? Why not have them both the same width? ( I can only think of one reason for this).

Also, the aft mount has that recess or cove into which the tang or tit on the ring fits. So despite the length of the aft mount (2" or more) that cove design suggests that Sako engineers want the rear scope ring mounted only in that one exact spot. But what if that position isn't exactly right for the scope I wish to use. Is there some special reason that every scope ring must mount in that exact position? There must be, but I can't figure out why.

Regarding the forward scope mount: the degree of taper is so significant that the scope rings won't even engage on the mount until you slide the ring about half the way up the mount toward the muzzle.
In other words, the aft 50% or so of the forward mount is rendered useless. I've never understood why. What good is it to design a mount that is two inches long fore to aft, and then render an entire inch of the mount unusable by making the degree of taper so abrupt that the rings can't engage it?
Why not design the mount with a much slower degree of taper, which would provide many more options as to where you can clamp the ring, since different scope tube designs and eye relief preferences might necessitate that the scope ring be mounted somewhere on the aft section of the mount?

Surely there must be some fairly sophisticated reasons for this design, but they are lost on me. Can someone please enlighten me.

I understand that the taper might be important for keeping the scope rings tight. I'm told they are "self tightening" since the recoil of the rifle wants to move everything forward, and the taper prevents any forward movement beyond a certain point. Is this correct?

Ok, so if this is true, then the taper idea should be superior to a non tapered (parallel) design. Except that companies like Ruger designed a scope ring locking mechanism that renders the whole "self tightening" issue moot didn't they?
In a different example, witness the picantinny rail design, where there is very little movement in any direction and the ring mounting positions seem endless.

Finally, and I don't even know how to word this "issue" properly, so let me give that disclaimer........doesn't having that severely tapered design lead to some geometry problems whereby the axis of the scope can get out of alignment with the axis of the bore quite easily?

So how is this tapered design so great? Is Sako simply using outdated engineering, or are the newer systems also flawed and I'm just not aware of it because nearly all my hunting rifles are Sakos?

I'm really not understanding it. Any help you can give me to understand it would be appreciated.

Thanks,
Rick

 

[stonecreek]

I'll give a try at some of the issues you raise.

1. While the little recoil lug on the rear ring does place that ring in a fixed position, many rings for Sakos do not utilize this lug, thus allowing the rear ring to be placed anywhere on the dovetail. If using Sako rings and you need the base further forward, many people simply grind the little lug off. The rings hold just fine under the heaviest recoil without the little lug. Besides, how is this lack of fore-aft positioning any different from a conventional drill/tap base which can only go in one place?

2. I'm not sure what kind of rings you used which will not clamp on the rear half of the forward dovetail, but original Sako rings have a nut on the left side which adjusts their width so that they will clamp anywhere on the dovetail. The same is true of several other rings made for Sakos.

3. Other "baseless" mounting systems like Ruger and CZ offer zero fore-aft adjustment, so how are they superior? While quite strong, they can only be loosened by shooting, not tightened like the Sako. The Weaver/Picatinny design works fine, but is not particularly pleasing to the eye on a fine sporter. Besides, it also can only shoot loose, not tight (not that that is a problem with properly installed rings.)

4. Sako did make ONE non-tapered dovetail in its short-lived Model 581 (a multi-lug rifle with a detachable magazine). According to the info here on the website they only made 1,500 of these before abandoning them. Whether they found the non-tapered dovetail a problem or they were abandoned for some other reason is unclear, but suffice it to say that all subsequent Sakos have used the same proven tapered dovetail which goes back to at least 1946.

I personally find the Sako dovetail one of the easiest and most foolproof mounting systems to work with. I've never experienced a failure of any kind on dozens of rifles with any brand of rings using it.

 

[hayseed51]

Geez - Louise Rick, sorry to hear the Sako dovetails are causing you so much anguish. Your post suprises me as I've always viewed Sako's mount pads as one of the most functional, handsome, and well executed features of their rifles.

I'm sure no Sako engineer, but over use and time, I do have some experience with them. I think they set out to craft a mount system that was very sturdy and precise. The dovetail's alignment with the bore is very good, but the windage adjustment of the original ringmounts allow even more precision, letting you get very close to horizontal zero, while keeping the scope's internal adjustments very close to the center. Mounts provide a modest amount of fore and aft adjustment - more if you want to grind the recoil lug off the rear or utilize the extended front mount... Add the fancy metal checkering on the pads and you have what has been considered the ultimate within the industry for quite a few decades.

I'm also familiar with the Ruger mounts that you seem to be fond of. My own experience with them has been fairly good, but in at least one case the receiver millings were not lined up axially with the bore worth a hoot. I've heard others have had the same problem. While on the subject of Ruger ringmounts, it should be noted that they provide zero fore and aft adjustment, since that also seems to concern you. Same as virtually any other common mount system...

Regarding the length of the dovetails, I can only observe that they are as long as the ring and bridge are. I don't have a guess why the rear is narrow and the front wider, but don't see it as a source of concern.

In years past, most people would select a scope and mounts that would work with the rifle. The Picitinny system has certainly given a lot of flexibility to the fore/aft aspect of scope mounting. It may come down to priorities in the end. I know I wouldn't want one of those ugly buggers perched on my rifle and guess I'll just plan on struggling along with the standard Sako mount.

Hope you can come to terms with it... Dick

 

[Anonymous]

Can't be much more logical than that, Rick. Maybe you should write to SAKO in Finland and ask if one of their engineers can answer your questions. Not getting on your case, or anything. You seem to imply that SAKO is setting someone up for proprietary use of their mounts (while other companies manufacture ones to accommodate as well). I'm trying to get my hands on the physics required to match what type of shooting you do? Perhaps the rear dove tail is a little "narrower" for aesthetics, or just a hair more bolt clearance, maybe? Regardless, IMHO SAKO has the alignment engineered just fine. Like Stonecreek says, since 1946. Even the Finns know the phrase "If it ain't broke, don't fix it". I would accept that theory in point and start working my way up from the dovetails. It was good to have your input.
Thanks,
S-A

 

[bossmustangace]

Ok, thanks guys. I understand everything you guys wrote and I appreciate all your comments. Let me explain specifically what I've gone through and perhaps you'll be able to help me.

First off, I should state that I own one Ruger rifle (a .22 mag) and I don't shoot it that much, but my point was simpy that both the Ruger and Picantinny styles are non-tapered and keep from moving through their own engineering. In other words, the taper is not essential to prevent rings from shooting loose on mounts. That's all.

Secondly, I own five Sako hunting rifles. I love them all, and have never ever had a failure with any of them (although a couple of the rifles are fairly new to me).

I can hear you in unison, "Ok, so what is he complaining about?"

Another point of fact is that I've been using Leupold rings and scopes exclusively, so maybe that has something to do with it. The set up was tricky for two of my rifles (more later if you want specifics).

And finally, my gunsmith is definitely down on the Sako ring system, and I get a lot of my knowledge through him, so I suppose I've been indoctrinated a bit by him. That is exactly why I phrased the post the way I did. I wanted people to extoll the virtues of the Sako system to me in order to refute some of the negativity he's expressed.

Other than an AR .223, I don't own a centerfire rifle made by anyone other than Sako. I've owned two Remingtons and eventually sold them to be replaced with Sakos, and the reason I did that is because I believe the Sako to be the best factory rifles you can buy. But I'm probably not like a lot of guys on this site. I do hunt a lot, as many of you do, but I don't own scores of hunting rifles, and I certainly have almost no experience with other brands, so many will view my opinion as valueless, and I'll accept that because I just don't have much diversity with other brands of rifles and scopes. Just Sakos with Leupold scopes and rings. Maybe that's part of the problem.

The problem comes when and if you wish to mount the forward ring on the aft 1/2 of the forward mount. With the Leupold ring, it simply cannot be done without modifying the ring. In fact, you can tighten the screw all the way down, and then slide the ring past the first half of the mount before it engages at all. Either there is not enough adjustment on the Leupold ring, or the degree of taper of the mount is too severe to allow the ring to engage.

I tried to mount a Leupold V-X3 L to Model 85 Classic and played heck trying to position the scope using the Leupold mount (part # 51036).
My gunsmith got it on there, and now it works fine, but not without some machining of the ring, which is quite tricky according to him. Apparently there are some funky angles to contend with.
If you look at that scope, it has a somewhat short tube and not a whole lot of fore-aft ring mounting options. I wanted to use that front 51036 ring and clamp it on the aft 1/2 of the front integral mount and couldn't do so because of the swift taper. The mount wouldn't allow it, or the ring wouldn't allow it; take your pick. So I chalked it up to Leupold designing a flawed ring mount maybe ( I know, I'm quick to condemn, right?) But my smith ran down a litany of "problems" with the Sako mounting system and that's what I've been hearing.

The fix: The smith had to mill down the base of the ring adjuster to allow that ring to engage on the aft portion of the mount. It worked, so I'm fine. But he went into a dissertation about the geometry of the mounts vs bore axis, etc and some of that I tried to get you all to dispell above and some of you did and I thank you for it.

Ok, so two final questions:

Do the Sako rings mount flawlessly in any position on the entire forward mount? Can I mount them on the back half of the forward mount without any "alignment issues" that divert the scope axis from the bore axis?

And finally, no one answered the question as to whether (and I think this is the most important part of the whole situation) the Sako system wouldn't work just as well with a slower degree of taper? And wouldn't a slower degree of taper allow rings to be mounted on the aft portion of the forward mount more easily, thus minimizing the previously mentioned alignment issues?

Thank you gentlemen for your thoughtful responses.

 

[Anonymous]

Rick,
I use the same scopes as you, and the Sako Optilock bases and mounts. I have never had a problem on my L61R Finnbear Deluxe .30-06 or one of the L61R GA's (7mm Rem Mag) that I actually shoot once in a blue moon. Here are some pictures of the GA. Everything works perfectly on both rifles. Don't know if the position of the mounts shown will help you, but I don't know what more to say, except that there are options in the bases that are available to possibly get you closer to what you want.
Ragards,
S-A

 

[Anonymous]

BTW, Just moving this scope over to this rifle. Had the Mil Dot (same scope) on it and switching to the Boone and Crocket Reticle, so don't nit-pick me on the space between the top and bottom rings quite yet :bigsmile3:Both are Illum 4.5X14X56, 30mm.
Thanks,
S-A

 

[hayseed51]

Ok Rick -

I think I understand what's got your smith's undies in a bundle about the Sako dovetails. It's a small thing, but more than just theoretical. When using the Leupold ringmounts, or any other non-windage adjustable mount, the further forward you set the mount in the dovetail, the further to the solid side of the clamp do you move the centerline of the scope. Usually if mounts are positioned close to midway on the pads there's plenty of internal scope adjustment to get on zero. Many shooters have perfect luck with this set-up.

Incidently, I just tried fittment of a front Leupold ringmount on an older Sako and it will clamp all the way to the back of the pad... Not sure exactly why yours wouldn't.

What any type a windage adjustable base will do is allow you to more precisely keep the axis of the scope directly over the bore. Millet and Conetrol provide independant front and rear adjustment. Original Sakos do as well, in addition to providing some fore and aft adjustment - for turret and bell clearance. Not sure about others.

In my opinion, a disservice was done when they gave up the windage adjustment in design of the Optilocks of both types. It would have been a great opportunity to allow precise fittment and also give some flexability in the fore and aft department using 30mm tubes.

The scope you have chosen, with it's relatively short center section could be challenging to mount on most any full length receiver. Understand that by saying 'I'm going to use this scope and these mounts on this rifle' you have really limited the flexability available. For example, the Millets in your particular situation, would likely have worked perfectly for tube fittment.

Rick, you seem determined to get a reply regarding dovetails fast taper opposed to a long slow taper, and how they might work in comparison. Don't think anybody here can speak for what Sako engineers theory might have been. A wild guess for the faster taper would be they didn't want to take a chance on somebody mounting them backwards... In any event - they are what they are...

Seems to me you recently bought an L57 or 579. If you can live with a 1" tube, why don't you get yourself a set of original Sako ringmounts to use on that rifle? I think your smith and yourself might be pleasantly suprised.

Best luck, Dick

 

[bossmustangace]

S-A,

Thanks for the pictures. That is one fine looking rifle. I'm pleased to hear that you actually shoot it from time to time. I've always felt rifles live to be shot, as well as to be admired for their beauty.

Also S-A, thanks for your comment on my Alabama buck. The rifle in that picture is my M85 in .25-06, which you have probably already figured out is the rifle that inspired this post. As you can see, it is working fine with great accuracy and no reliability issues so far. However, as I mentioned, it took some milling of the stock Leupold ring mount to get there.

Thanks for your help,

Rick

 

[bossmustangace]

Hayseed,

Thanks again for commenting on this post. It's clear to me that you understand exactly what I was getting at in my original and follow up posts, which is hard to express in words, but you did it very well when you wrote, "When using the Leupold ringmounts, or any other non-windage adjustable mount, the further forward you set the mount in the dovetail, the further to the solid side of the clamp do you move the centerline of the scope. Usually if mounts are positioned close to midway on the pads there's plenty of internal scope adjustment to get on zero. Many shooters have perfect luck with this set-up."


You are exactly correct! If you really stop and examine the geometry behind what is going on there, you'll begin to understand that there is a "sweet spot" for mounting any scope on the dovetails if you don't have windage adjustable mounts. So learning that, my mind immediately wishes to conjure up a "better mousetrap", whereby this issue is dimimished or eliminated completely. It still seems to me that this effect we are referring to (whatever you wish to call it) would be minimized by decreasing the rate of taper. In other words, and this is getting very theoretical now, the closer you bring the taper to parallel (or zero degrees taper), the less you would need the windage adjustments. Do you follow my logic?

If so, re-read my first post and it might make a bit more sense now about the non-tapered designs. They don't have this issue (they trade this issue for others I think). So in that first post I was essentially trying to assertain if, in the general opinion of the very astute followers of this forum, they believe that the single and only reason for the taper is to prevent forward movement during recoil. I don't really know, but let's assume it is. Then there only needs to be enough taper to prevent forward movement, and any more taper than that is a detrimental to the geometry issue. Likewise, any less taper allows things to move forward, which is even worse.

As an aside, maybe that is why the Sako engineers put that tang and cove on the rear mount. Maybe that is exactly where they want the rear ring to mount to preserve the geometry of the system. You know?

Anyways, what a great forum that I could even try to express a concern like this and get timely, well thought responses from other enthusiasts overnight. I love this forum!

Not to be long-winded, but I found your comment that your Leupold front mount could be clamped in any position on the forward pad to be interesting. My mounts (#51036s) simply wouldn't do that.

Of course I could get the rear mount to clamp anywhere on either of the front or rear pads, but the designated front mount would never work on the rear pad as it's obviously way too wide and not designed to be used there. More importantly, the front ring mount would not engage on the aft half of the forward mount pad. I tried a few different sets of 51036s and they were all the same. Strange.

On my first rifle, everything installed just about in the center and there were no problems. Super easy. But I'm completely obsessive about uniformity from weapon to weapon, and I likely handicap myself in that regard. So I experienced some fitment issues on some of my other rifles because my choice of scope and rings was based more on uniformity than practical application. The fact that I insisted on using the same ring and scope combination, no matter how compatible the components were, is probably what drove my smith to make those comments.

Anyways Dick, thanks for sticking with me on this hard to follow post. You never know, one night three years from now someone might stumble across this post and it might help them somehow. I appreciate everything you and all the other moderators do for our beloved website.

Regards,

Rick

 

[hayseed51]

Ok Rick -

I'll hang in there a little longer, although the theoretical regarding the fast vs slow taper seems to be getting close to the 'how many angels can you fit on the head of a pin' thing. Would a slower taper work? Maybe...probably. But the essential fact is the Sako dovetails are what they are and what they created back around 1940. That Sako engineers didn't anticipate how scopes might change in the decades to come or what aftermarket mounts might be cooked up to fit their rails, sure doesn't seem like 'incredibly flawed' design to me...

Interestingly, I believe Sako's dovetails were originally used with their non-windage adjustable and non-split rings. Right about the mid-40s I think it became apparent that a revolution in scope design would soon make the non-split rings a no-go. I think it was actually Firearms International's designer Russ Moure that came up with his 'Armstrong' rings for Sako dovetails. They were adopted by Sako and became what we all think of nowadays as 'original' Sako rings, complete with the windage adjustment. While most scopes of the day were likely 4 or 6x, with lots of adjustment, I think this could be viewed as Sako engineers recognition of, and solution for the small geometry problem when using non-windage mounts. In my mind it was a perfect solution, and remains so, at least for 1" tubes without huge bells.

I like Leupold - scopes as well as mounts. However, for a guy like you that sweats the small stuff, I think you should recognize that their ringmounts are a compromise. The geometry situation that troubles you is a result of their design rather than some intrinsic flaw of the dovetails, in my opinion. While I can understand and appreciate the value of haveing the same scope and mount setup on all rifles for shouldering, I think you chose the wrong saddle to put on the horse, if you continue to worry about the geometry aspect.

FWIW, I always considered the recoil stud in the rear ring to be a belt AND suspenders sort of deal...

Best luck, Dick

 

[bossmustangace]

Thanks Dick,

I appreciate all you input.

Rick

 

[mattimoose]

I don't think it's any more flawed than the 100 or so years of mahine tools with morse tapered shanks. makes perfect sense to me. my cousin Kari fell hard on his SAKO 75 Stainless on a rockpile on a riverbank and Smashed his red-dot all-to hell in it's 30mm rings, so he took the 3-9 bushnell trophy still in the 1"rings, slapped-it on with no test-firing and shot the biggest deer i'd ever see, right where he aimed, 3 years after he'd taken that scope-off. Relocation repeatability, 100% I love SAKO's integral dovetails and think all rifles should have them.

 

[71Scamp]

I don't think it's any more flawed than the 100 or so years of mahine tools with morse tapered shanks. makes perfect sense to me. my cousin Kari fell hard on his SAKO 75 Stainless on a rockpile on a riverbank and Smashed his red-dot all-to hell in it's 30mm rings, so he took the 3-9 bushnell trophy still in the 1"rings, slapped-it on with no test-firing and shot the biggest deer i'd ever see, right where he aimed, 3 years after he'd taken that scope-off. Relocation repeatability, 100% I love SAKO's integral dovetails and think all rifles should have them.

I've been using Sako rings for 45+years and choose to use them exclusively where I can. I'm OCD enough to have purchased Sako ring/mounts to modify by using EDM to wire off the rings so that I can have 30mm rings TIG welded onto the dovetail mounts. This because Sako has chosen not to provide 30mm rings for the L579/AII/591. I even purchased a precision 30mm SS rod to use to assure proper alignment. I will NOT use anything other than Sako rings! I've never had a scope that I couldn't mount and get zeroed, that failed to return to zero after the off/on operation (I favor Leupold). And yes, I'm the guy that outbid you on EBay.

71Scamp

 

[71Scamp]

I've been using Sako rings for 45+years and choose to use them exclusively where I can. I'm OCD enough to have purchased Sako ring/mounts to modify by using EDM to wire off the rings so that I can have 30mm rings TIG welded onto the dovetail mounts. This because Sako has chosen not to provide 30mm rings for the L579/AII/591. I even purchased a precision 30mm SS rod to use to assure proper alignment. I will NOT use anything other than Sako rings! I've never had a scope that I couldn't mount and get zeroed, that failed to return to zero after the off/on operation (I favor Leupold). And yes, I'm the guy that outbid you on EBay.

71Scamp

I forgot to mention that I have also 3D modeled pedestal mounts for L579/AII to allow the use of Sako (or Talley) rings in a forward mount condition ala "Scout rifle". I received the 3D printed prototypes today. I will end up with multiple pairs, if anyone is interested. They should also work for NVDs.

 

[Webphut]

The integral tapered dove tail design eliminates the 6 degrees of freedom.

The recoil lug on the bases, once inserted into the recoil lug slot, is to keep the scope eye relief and planes locked in place for repeatability when removing and attaching the rifle scope to the rifle.

On the Opti Lok rings, the idea of the spherical bushings is to align the scope tube to the center of the rings, hence keeping all four planes parallel to one another.

If you are ever able to have the opportunity to use CAD software, you may get an idea of degrees of freedom and planes and probably too soon now, but possibly beam theory too applies to Sako’s design.

 

[mattimoose]

I've been using Sako rings for 45+years and choose to use them exclusively where I can. I'm OCD enough to have purchased Sako ring/mounts to modify by using EDM to wire off the rings so that I can have 30mm rings TIG welded onto the dovetail mounts. This because Sako has chosen not to provide 30mm rings for the L579/AII/591. I even purchased a precision 30mm SS rod to use to assure proper alignment. I will NOT use anything other than Sako rings! I've never had a scope that I couldn't mount and get zeroed, that failed to return to zero after the off/on operation (I favor Leupold). And yes, I'm the guy that outbid you on EBay.

71Scamp

Right-on, it's good to see a like-minded person. I am currently trying to figure-out improved scope mounting for my Valmet 412 S. While not tapered, it has one big woodruff key in the back that assures zero. It's just that it's too high and too heavy for my liking. And yes, where SAKO is unavailable Leupold is best.