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Sako L579 action in target rifle hybrid

Sako Collectors Club Discussion Forum

Hi guys,

I picked up a .308 Win target rifle with the Sako L579 single shot action.
I am unsure if the action has a magazine cut out, I am saving that surprise for later...
30" barrel is aftermarket with 1:12 twist K. Hill gunsmith.
The stock is unknown manufacture but appears to be based on an aluminum extrusion RHS. It is designed for bipod mounting and the butt stock is a bag rider.
The trigger is (as yet) unknown but is one of the sweetest I have used.
It has been set up for both aperture optics (Gehmann D75 iris rear, Parker Hale front) and is fitted with a 20 MOA rail screwed on top of a one piece machined steel flat rail which seems to be countersink drilled for mounts. Awful...

I have been using a .308 24" Savage Model 10 1:10 twist but the short barrel gave slow muzzle velocity particularly punishing beyond 600 yds. Load is usually 155gn x 46gn AR2208 but I tried various projectile weights for higher MV. Sierra 125gn flat base were great at 300 yards but dropped below subsonic at 900 yards. We live and learn... I bought the Sako for the 30" barrel, not the receiver.

I mounted a Sightron Sii 10-50 x 60 on the "Sako" and took it to the range on the weekend and shot 800 yards.
The rifle holds 1/4 - 1/2 MOA on windage (10 & 11 shot strings) but I was having trouble with elevation +/- 2MOA.
The scope mount rail is sliding on the Sako dovetails, it moved rearward about 3/4".
The rail thrust screws are tiny 10-22 mushroom head cup screws (1/8" Allen key)
The front screw failed and the head broke off...
I will replace the thrust screws with 10-22 machine screws grade 12.9.. on order.

It's unlikely that I will ever shoot beyond 900 yards so maybe I can get rid of the Picatinny 20 MOA rail?
It doesn't make much sense to me to be set up minus 15 MOA on the scope at 100 yards with the rail but only need 20 MOA adjustment on elevation to get 900 yds.

Thoughts? Keep them cheap, please.


Well-Known Member
That is "interesting".

It looks like a steel Hillver/Tasco WC bridge mount base has been used on the Sako dovetails, and then instead of using the matching rings a picatinny rail has been screwed onto the bridge mount. If I am right the bridge mount base shouldn't slide on the dovetails if pushed up tight to start with, as it has the taper that matches the Sako tapered dovetails. They usually also have some lock screws on the RHS as well.

That ridged rectangular piece looks like a mounting block for a Central No.4 aperture sight or similar.

I can only just see what looks like a trigger shoe, so I wonder whether it is fitted with a Canjar set trigger.

That stock looks pretty wild.

16431149393771874486352.jpg Some more happy snaps for your added viewing amusement....
The front rail screw has a 10-22 thread sling stud in as temporary until the 12.9 cap screws arrive.
We are shooting 900 yards this weekend and I don't want to pull it apart then re-assemble because I'd have to sight it in... so there won't be any nude photos until later.
I put some lead shot under the vertical screws which attach the pic rail to the (Hillver?) dovetail adaptor. The screws squish the lead direct to the dovetails which might stop the sliding.

We shall see...


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That is "interesting".

It looks like a steel Hillver/Tasco WC bridge mount base has been used on the Sako dovetails, and then instead of using the matching rings a picatinny rail has been screwed onto the bridge mount. If I am right the bridge mount base shouldn't slide on the dovetails if pushed up tight to start with, as it has the taper that matches the Sako tapered dovetails. They usually also have some lock screws on the RHS as well.

That ridged rectangular piece looks like a mounting block for a Central No.4 aperture sight or similar.

I can only just see what looks like a trigger shoe, so I wonder whether it is fitted with a Canjar set trigger.

That stock looks pretty wild.


The rear is a Central post with the Gehmann iris.
The trigger is probably not a Canjar, it doesn't push to set... it has a wide alloy shoe which is new to me but is comfortable.
It'll be 500 grams ++ but my experience is it doesn't move much under pressure (zero travel) and the trigger stop is perfectly set on the release point, no sudden tension relaxing. Each shot is a surprise release and for me that's the best set up to avoid flinches or muscles tensing anticipating recoil. So far so good.


Each shot is a surprise release and for me that's the best set up to avoid flinches or muscles tensing anticipating recoil.

This, to me, is the number one cause of accuracy problems in 90% (or more) of ALL firearms. Tho a 500 gram trigger is much to light for my shooting needs and applications. It’s about trigger control on a neurological level. Muscle tension is triggered by the brain. Spaher related to this recently on the subject of game loss…It has a huge relationship to accuracy and success in the field.
Thanks for mentioning it!
Lots of nice rifles are blamed to be pigs but were just in the wrong hands... a Brno .270 "couldn't hit a dinner plate" until an experienced roo shooter showed the owner he was timing the shot and flinching.
A good training technique is get a friend to load cartridges into the firearm, some live, some duds... the shooter shouldn't know what will go bang or click in any order...
This works well with repeaters or even handgun revolvers... semi-auto not so good.
It'll highlight a spasm or flinch big-time. Mostly it'll be trigger hand squeezing the blood out of the grip pushing sideways but I have seen gun-shy flinches pull low enough to miss an NRA target at 7 yards.
I'm not immune myself; an old 12 guage hammer gun I have sometimes misfires and I know I have grunted in anticipation of the recoil but a shotgun is a delberate trigger pull.
...all good skilling.


Well-Known Member
Ok, so the bridge mount is of the Hillver/Tasco World Class/Tetra type - that domed hex-headed screw is typical for the post-style (as opposed to turn in style) rings. I'm not sure what was done with the front screw, looks completely different. Lost perhaps?

I just went back a re-read that the scope mount base was sliding rearwards on the tapered dovetails - that is interesting. Usually upon firing the rifle recoils backward and the scope (particulalry a big scope like the Sightron) wants to stay put, and tends to cause bases or rings to slide forwards. This is where the Sako tapered dovetails are terrific as under such movement they just wedge even tighter. I'm at a loss as to why the mount would be sliding backwards.

The trigger shoe looks exactly like the ones I have bought from eBay and put on a couple of my rifles, so it is likely that you have a standard Sako No. 4 trigger, but given the mixed perigee of this beast nothing is guaranteed.

Keith Hills is a gunsmith in Cowra NSW, operates as Keith Hills Gunsmithing Service, and is on Facebook as KHGS.

The front screw on the Hillver broke...head came off clean ...and the sling swivel is a temporary until I get some 12.9 cap screws.
I have some 30mm Bushnell twist lock rings I might adapt to post style and scrap the 20 MOA pic rail.
You're correct, the scope slid forwards with the mounts and rail... I need to see if it locks up TIGHT on the dovetail tapers but I don't think it does and from what I observed the mounts slide forward (up the barrel) easier than off the back. Counterintuitive.
I don't want to drill and tap the receiver but I won't put up with feeble or unreliable mounts.
The idea the silly little mush head screws with a steel washer with a groove cut in it as a clamp will hold up under repeated recoil is a bit agricultural. I will pull it down next week to investigate options... there is a drilled hole on top the rear dovetail, maybe a good spot for a locating pin?


Well-Known Member
If the bridge mount can slide forward on the tapered dovetail on top of the action something isn't right - I wonder if some bubba has used a non-tapered bridge mount from a Tikka or similar. You will only know when you pull it off.

You could use a pin in that little recess milled at the back of the dovetail, but if the correct mounts are set up properly there is no need.

I use the Hillver/Tasco WC bridge mounts and post style rings on all my L461s. I slide them on from the rear, give a small tap with a hammer block of wood to wedge tightly, then screw in the side screws. I like this style of base and ring as you have significant windage adjustment in the rings, multiple ring height options on the same base, and I can quickly swap scopes between rifles by sliding the whole base/rings/scope assembly off the dovetails. If a scope is taken off a rifle in this way and replaced it is usually within a few clicks of zero.

Hmmm... the plot thickens.
I'm sure if you looked at the rail in your own mit you'd spot this a lot more quickly than I would.
The rail is stamped "Tasco" but no other I.D. that I can see.
It looks like the dovetail slot in the rail is machined on a slope (taper) but probably the most interesting examination is the front dovetail slot on the rail is broken away just rearward of the screw. You can just see this is missing in the Right Hand view previous photo. My guess is that the rail is distorted...it is certainly broken.
The missing bit would be the thick edge of the wedge of the taper.
Any wonder it is sliding under recoil.
To my way of thinking it's a bit of a design flaw that there are a few "engineering" considerations adding up to the failure.
1. The dovetail taper design notches the component which creates stress concentration
2. The highest stress will be at the thick end of the wedge which is under constant load and shock loading forces.
3. The material thickness from the apex of the machined notch to the outer side is about 1mm thick.
If I buy a replacement it won't be this Tasco design.
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Well-Known Member
I'm not sure I quite understand- is it this small section that you think has broken out?


I would have thought that even if that small section was broken out the wedging action of the rest of the tapered base would still hold. The bearing length along the dovetail would still exceed that of factory Sako rings.

Does your base have the taper like these ones?



The different styles - the top and bottom are post style, the middle one is Redfield/Leupold style turn in front/windage rear.


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Thanks for the photos. I am jealous!

The Tasco mount seems to nearly match the one you're pointing to with the pen. The broken piece is exactly where you're pointing. The inner edge of the break is at least 1mm clear of the front dovetail edge on the RHS. The LHS is clamped up due to the clamp screw. 16432686632101342120669.jpg

It appears the "tapers" cut in the rail are almost parallel. I think you're correct that the rail is for a Tikka.
It doesn't look like the taper is anywhere near even touching the rear dovetail which explains why I can push the rail forward to remove it.

P.S.: the screws are 10-32 UNF threads
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Ok. The shoot today was an epic fail. +/- 2 MOA and the Tasco came loose first shot. Even though the screws were super tight the rail moved 10-15mm.
The rifle receiver dovetail mounts are NOT both tapered and at the tips measure:
Front: 20.5 mm wide end, 18mm narrow.
Rear: Parallel 12mm
It all seems "factory" and no marks from back yard machining. 16434447528621652796950.jpg

The Tasco rail is kind of tapered at the rear but seems almost parallel at the front mount, in any case it can't clamp positively in a locked taper. It is way too wide. 1643445449715396947700.jpg

I can't see a way to cater for both clamps being different and point contact only.

I am tossing around a $350 Contessa 20 MOA Picatinny rail that is built for the L579 or re-working on a Hillver for about $200.


Well-Known Member
That is very weird. I do wonder whether the rifle dovetail on the rear receiver ring has been machined, as I think (?) the top should probably be stippled like the front receiver ring. Have a look at the photos in this thread on Saubier: http://www.saubier.com/forum/showthread.php?t=29176

It does also look like that rear dovetail is parallel rather than tapered. Can you set a straight edge (like a steel ruler) against the side of the front and rear portions of the receiver dovetail?

While you have a straight edge out, set it across the top of the receiver - is the upper surface of the rear receiver ring lower than the front ring? If it is then it's very likely it has been machined - why I would have no idea.

If the rear receiver ring dovetail has been machined then the value of the action (not necessarily the function) has been severely compromised, and it possibly opens up some remedial options that wouldn't normally be suggested on this forum such as:

1. drilling and tapping to enable a mount base or rail to be properly anchored to the top of the action. If the rear receiver is now machined lower it may need shimming to bring back up to correct height

2. machining the front receiver ring dovetail to match the height and width of the rear ring, assuming that there are commercially made rings to suit. A recoil stop would need to be incorporated into the base or one of the rings.

This is one of the strangest set ups I've seen. I don't know Keith Hills or his gunsmithing work, but I would be very surprised if he was involved in this scope mounts work. It seems like a backyard try different things as you go job.

I put the straight edge on... the top surfaces are "level" with each other and the bottom undercut of the dovetails is level also. My guess is the root is the important bit although I noticed the mount doesn't fit down on the root.
The rear dovetail root undercut is parallel with the top face...so they didn't just machine off the top wide end.
If I place the straight edge along the root of the front dovetail it aligns with the rear-most root of the rear mount.

This set up makes sense to me, the parallel rear dovetail allows the front mount to drive up HARD and lock on the taper but would require a bit of patience to get the correct location and fit. The rear mainly just holds axial alignment. It'd be OK if the mount had the matching machining...but it doesn't.

I'm not in a hurry to make a decision to fix it.
My first quick fix is to insert a 1mm thick shim strip front and rear...if it holds that'll do for a while.
I anticipate it will end up a hybrid with Talley mounts but am toying with the idea of a fabrication of my own.
I would buy a Contessa rail if the rear machining matched mine.
This is as Finnish as a 5 sided nut.

Having worked for a Finnish/Swedish multinational OEM for a long time I don't think this is too unusual. It was a philosophy to capture after-market spares for equipment because nothing was interchangeable with other brands; special cylinder rods and clevis ends, triangular 18V batteries...but nothing superior in function, just "different".
I used to joke about a Finnish blacksmiths anvil selling features of:
- light weight / portable / folds for easy storage
- 75 dBa noise level when not in use
- two piece alloy construction
- takes 4 AA1/2 batteries (sold in packets of 7)
- CE Certification

...and now I own a lemon.
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I partly disassembled the stock from the receiver. The wide trigger shoe needs to come off to take it right out but I was able to see the receiver is a "genuine" single shot design, not pinned or blanked. So I have a rare lemon!

After re-fitting with shims the Tasco mount seemed pretty good. I assembled the pic rail with Siii scope and put a few heavier loads through (MV 3100 x 155gn) to see if it stayed in place.
The pic rail failed at the front screw.

The alloy pic rail screws placement was less than ideal but I think the main issue was the depth of the countersink for the screw head resulted in a crack in the alloy. I am unsure if this was excessive tension on the screw or recoil reaction.

The scope mount was just forward of the front screw. It seems to be a limitation with the medium action... the mount centres are relatively close compared to the calibre .308 you can shove into it. I guess back in 1960 they didn't know that scopes would become as big and heavy as they are these days.

Watch this space for more exciting episodes in the series of how to get it wrong.
...just to give you an idea of the kind of forces on a scope mount under recoil...
This 10mm hole was ripped out of the alloy Picatinny rail at the front mount.