Anyone bedded a Sako 85?

Improving and repairing firearms. Rifle bedding, barrel work, stock replacement and other ways to improve your firearms.

Anyone bedded a Sako 85?

Post by Flyer » 19 Dec 2016, 9:11 pm

This thread pretty much highlights the issues I'm having, but it's essentially a random flier, always to the top left of the group as in the image below: viewtopic.php?f=3&t=7221&p=113246#p113246

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This was a 5-shot group at 200m, but I have lots or similar groups, always with that top left flier, or a double group top-left/bottom right. I'm fairly confident it's a bedding issue.

This is what I've found:

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Though hard to see here, the rear action screw hole is not centred - it is about .030" off to the right (towards the top in this photo). Note the action screw housing marks (semi-circles behind the screw hole) in the wood showing the action has been jumping around.

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There are marks on the right-hand side of the inner stock (on the left in this photo) where you can see the action screw housing has been hitting/bouncing off the wood. You can also see where the action screw has been rubbing on the same side. Note the two light rub marks to the left of the screw hole in this pic.

What I believe is happening is the rifle is recoiling into the right side of the wood - throwing a flier to the left - and then bouncing the action back into the middle of the stock where it shoots consistently for another 3-4 shots or more until it creeps over and hits the stock again.

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Anyone here familiar with the Sako 85 action knows they have a complicated mish-mash recoil set-up with a recoil plate and two recoil lugs.

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This looks like a real bastard to bed!

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It has a recess for a Tikka-style floating lug, but is useless on the Sako. I wonder if a Tikka recoil lug could be retro-fitted with a bit of stock work?

So I've ordered some stainless tubing (9.54mm x 1.6mm) and am going to redrill that rear action hole to centre it, using the stainless sleeve/pillar.

I can either set the stainless sleeves in the stock, or leave them floating (CZ527 style) - how much clearance do I need between the action screw and the inside of the pillar? I was thinking a tighter fit might keep the rifle centred without using any bedding compound. The stainless pillars have about .008" clearance either side (.016" larger ID than screw diameter), and my preference would be to have them floating (though compressed against the action and trigger guard).

Is this a good idea? How on earth can I bed the rifle using bedding compound (Devcon) without entirely sealing that front recoil plate?

Does anyone have any ideas how to bed a Sako 85?
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Re: Anyone bedded a Sako 85?

Post by Wm.Traynor » 20 Dec 2016, 1:26 pm

I said, "Yes", to myself on seeing the topic heading but the sight of that recoil plate thingamajig, put an end to any idea of helping. The 85 I owned was bought in '97 and did not come with such hardware.

However, I have a few general thoughts, if you will permit:-
The take-down bolt being in contact with the stock is not good and it could be that the action holes, front and back, are not parallel. Test by screwing in firmly by hand, a couple of cheap bolts with shank length of say 50mm. Check for parallel by eye and by measurement, top and bottom. By eye; position your head at the rear of the action. You will soon see if the shanks are parallel; move your head from side to side.

If that checks out, then the stock holes might be out. At this stage I would remove the wood that the tang is recoiling into. You could take a chance then and shoot it and see :) or you could do a bedding test first. If you are interested, tell me and I will look in my posts for it.
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Re: Anyone bedded a Sako 85?

Post by Chronos » 20 Dec 2016, 4:20 pm

I've never owned a Sako let alone bedded one but for what it's worth take it to a smith and have him pillar and glass bed it or leave it alone. It's a job that needs to be done properly on such a good rifle.

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Re: Anyone bedded a Sako 85?

Post by Flyer » 20 Dec 2016, 5:16 pm

Here's the dilemma: the factory set-up is clearly very accurate - when it works. I'm loathe to mess with it. However, until I fix the rear tang issue, those fliers are going to drive me nuts.

I'm thinking of doing this one step at a time to evaluate each change without going too far . . .

My first step would be to redrill the rear hole so that it is centred. The hole is 8mm (the action screw is 6mm) and I have some 9.5mm (3/8") stainless tubing on the way. I'd drill the hole to 9.5mm (3/8") and pillar it with a floating sleeve. My CZ527 has a similar set-up on the rear action screw (floating sleeve/pillar) and shoots very well. This pillar would allow me to tighten/secure the rear action screw a bit more.

In addition, I would relieve (radius) a small amount of wood around the rear mount/tang - as suggested - to prevent it coming into contact under recoil, or if the action moves a little in the stock (which it may or may not do after pillar tightening the rear).

My next step - at least what I'm considering - would be to brass pillar the front action screw. This pillar would be about 15-16mm in diameter and epoxied into the stock. It would sit directly under the recoil plate and sandwich it between the receiver to provide metal-on-metal contact. Right now, the receiver sits on the metal recoil plate, which sits on the wooden stock, and can move/flex depending on how the wood contracts and expands under different conditions (temps and humidity). A wide brass pillar in the stock would not interfere with the recoil system, but would provide a stable platform for the recoil plate to sit on.

Now, none of this entails bedding compound, would require minimum modification to the stock, and would not interfere with the original design. Does anyone see any problem with this? Thanks.
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Re: Anyone bedded a Sako 85?

Post by Apollo » 20 Dec 2016, 6:23 pm

This is the bedding work done to my Sako 85 .243W Laminate Varmint by Hennessy´s Gunsmithing Service Townsville. The rifle was purchased secondhand so I don't know what it looked like prior to this work.
However, my Sako 85 .204R Walnut Varmint has the same front recoil plate as you have pictured plus a steel washer 0.020" thick on the stock under the rear tang the exact shape of the tang around the mounting hole.
When I first ever removed the stock I did a rough measurement of the screw tensions. The front was about 90 inch pounds and the rear about 50 inch pounds. That was the way it came from the Sako factory.
Neither rifle has any pillars installed.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 20 Dec 2016, 9:58 pm

That's interesting. Mine's a .243 Bavarian, which I bought second-hand. It was in near-new condition, despite being maybe five or six years old. There's no rear washer on mine, as you can see.

If your 204 walnut was new, and the rear washer is from the factory, then that suggests Sako may have known about issues stabilising the rear action on older, wood-stock models. Maybe a rear pillar or bedding is the way to go?

As for the 243 laminate, it's hard to tell from the photo, but is that a metal plate embedded in the bedding compound for the action screw housing to sit in as a recoil lug? Or has the entire front action been bedded in bedding compound?

How do they both shoot?
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Re: Anyone bedded a Sako 85?

Post by Apollo » 20 Dec 2016, 10:50 pm

First thing I would do is find a piece of steel 0.020" thick and make up a washer, then tension the action down a little more than you have been doing. I realise the Sako suggestion of tension but as I said mine had a hell of a lot more tension especially up the front.

My 204R was new and that is the first time the action has been out of the stock.

The .243W Laminate. No there is nothing embedded in the bedding compound. The entire front section, including the parallel section of the barrel is just in bedding compound.

They both shoot very well, the 204R about 0.4moa and the 243W is better than 0.3moa. I have a Tikka T3 Stainless Barrel that I am testing at present on the Sako 243W using Berger 90gr Boat Tail bullets that have been pointed and moly coated, using about 42.6gr AR2209 and these will group 5 shots around 1/2" at 200 metres. This is my 300 metre target rifle for competition. Bullets are seated to be around 0.020" jammed into the lands. The Fluted Sako Stainless Barrel does even better but also has less rounds down the tube, like just 125 rounds so far. The trigger on this has been very much lightened to well under 8ozs pull.

For general use varminting I swap to an older Blued Tikka T3 Barrel that has seen about 1,200 odd rounds but still shoots 0.5moa, Not as good as the stainless barrels but very useable. All three barrels headspace exactly the same and the chambers are identical so any cases fired in one work in the others. I use Lapua Cases for the two stainless target barrels and Winchester for the blued varminting barrel, don't mind if I loose a Winchester Case out in the paddock but so far in many years they are all intact.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 20 Dec 2016, 11:30 pm

When you put the 204 back together, did you use the same tension - 90/50 in lb?

The problem with a metal washer is having to cut the wood underneath for it to fit nicely; you'd probably have to remove a fair bit of wood under the tang and bed the washer with bedding compound. It might be easier to use bedding compound alone, possibly with a pillar support.

With your 243 laminate, there are two levels of bedding around the tang - a lower step around the rear action screw housing, and a higher step under the tang itself . . . does any part of the rifle touch the walls of the bedding (upper or lower level) or are the tang and action screw housing both clearanced on all sides, sitting only on each floor of the bedding compound?

I'm trying to figure out if the rear should be nice and snug, or if there should be a gap behind the tang, the rear action screw housing or both to prevent the rifle recoiling into the back of it and chipping the compound or wood behind the tang. To my eye it looks clearanced around each level.

As for the front of the receiver, I know it's only a 243, but I'm surprised the bedding compound takes the full recoil. Or maybe I shouldn't be . . . The way it's done, it looks like the bedding bridge in front of the action screw absorbs recoil, while the action screw housing itself is also a recoil lug, spreading the recoil over two surfaces. If it works, then it is hard to argue with.

This is a four-shot test load I shot last week (100gr Sierra Game King, 39.5gr of 2209), so my rifle definitely has potential . . . when it's behaving itself.

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Re: Anyone bedded a Sako 85?

Post by Apollo » 21 Dec 2016, 10:29 am

Yep, I used the same tension as it was in the first place and the same for the .243W. Will check accuracy next time I set up to do some further load testing.

The washer on the .204R is just sitting on top of the timber, it is a tight fit around the outside so much so it won't fall out. I had to lift it to grab it at one end to remove it.

The bedding in the .243W is a tight fit all around including the sides, there is no room for anything to move side to side or even forward to back. It takes a little pressure to remove and/or replace the barreled action in/out of the stock. When it's all assembled there are no gaps anywhere including around the parallel section of the barrel. Done like any other bedding I have done or seen, bedding compound applied and then action/barrel pushed in and held in place with probably slight tension then excess material removed all around then let set. As my own Gunsmith said when he was working on it "very good bedding job" .

Looking at the shiny parts of the bedding it's the whole bedded part front and back including the section that looks like where a recoil block (like the Tikka T3) could be fitted that is taking any recoil affect. Without the action screws installed you cannot move the action sitting in the stock in any direction other than up and out of the stock.

I don't know if this has any relevance but when my Gunsmith had my old Sako S491 22/6BR he added a washer under the rear tang as he said it wasn't sitting flat when the action was held down by just the front section. It is not fully bedded just had pillars installed some time ago. Super accurate single shot. In his view don't touch what ain't broke. On this one I tension the action down front and back to 50 inch pounds. That was when I had a new 28" 1:8 twist 22BR barrel chambered. BTW, he is the consultant gunsmith for the NRAA.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 21 Dec 2016, 11:43 am

This is all great info. I'm quite remote, so gunsmithing options are limited (non-existent if you count Sako experience). So unless I head to the big smoke, I'm going to have to tackle this myself with a bit of help from a machinist I know who has a fair bit of bedding experience. I've bedded a couple of rifles myself (and haven't ruined them!), so I don't mind touching this one.

I like that your 204 retains the original recoil plate design with the rear washer mod and still shoots lights out. I've noticed that if you tighten the wood screws too much on the recoil plate, it tilts it up slightly where the action sits, and you can feel the pressure as you tighten down the action screws. This tells me it might be worth bedding the recoil plate/lug, with or without a brass pillar.

Whatever I do, it's clear the rear action needs to be bedded properly. I can try a snug fit to begin with, and if that doesn't work, it's no real effort to remove some compound around the edges to clearance the tang and action screw housing. It seems the most import thing is to be able to apply some pressure to those action screws to stop the rifle jumping around in the stock.

I really appreciate the photos and information you've provided - thanks.
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Re: Anyone bedded a Sako 85?

Post by Apollo » 21 Dec 2016, 12:27 pm

BTW The .204R rear washer is not a "mod" as that is the way it came from Sako. Pretty sure you realise that. I have looked at the parts list for a Sako 85 and so far I can't find it listed anywhere.
I have not fiddled with the front recoil plate or it's screws, I know it doesn't move if touched.

It's nice having a Gunsmith available that's only a hours drive away, even though he's semi retired and not taking on new customers really. Small jobs are done on the spot and always a yarn involved to pick up a few more tips for improvements to test even though he's not a Benchrest shooter.

I've been playing with a .243W for a lot of years from a Brno 601, Tikka T3 and now Sako with bullet weights from 55gr to 100gr and found the best accuracy with bullet weights from 70-90gr and the 90gr for target shooting. I've got some Berger 95gr VLD's and they just don't want to group for me in any barrel, they are long and behave like they are on the edge of stability as they should since they are rated for a 1:9 twist barrel. I'll use them up with a fast twist 6mmBR barrel in the planning stage. All my three barrels are exactly 1:10 twist, I'd love to try a faster twist rate for the .243W but then I'd be out of "factory class" qualification.

Best of luck with it all and hope you see some improvements sooner rather than later.

Oh, your good group you pictured is pretty much what mine does at 200m on a perfect still cool day, different story when I get to a competition and the winds always seem to be blowing combined with mirage brings things unstuck a tad but still good enough for a couple of wins against some other calibres like .308W. Being able to test and practise at home has a lot of advantages picking the good and bad times.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 21 Dec 2016, 9:18 pm

Yeah, you read my mind - I was thinking of emailling Beretta to see if those washers are available as spare parts and what the recommended procedure would be to retrofit them (if there is one).

I've had a bit of luck with the 95gr Sierra Tipped Match Kings. All the ballistic programs I ran said they would stabilise in my Sako, which they have (out to 200m so far). I measured the barrel and it is actually a 9.75 twist.

This is a good stability program for modern plastic-tipped bullets (which are easier to stablise than hollow points, FMJs and soft points, as they are generally lighter and have more rearward weight bias for the same length projectile):

http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

Most of the 95gr TMKs in my box of 100 were around 1.165"-1.167" in length. The plastic tips are about .155"-.160" in length. Sierra says they are designed for 9 twists, but I have read elsewhere they will stabilise in standard twist barrels where the 95gr Berger VLDs and Match Kings won't. Only downside is they are about $80 for 100. On paper, they are the best thing out there for a standard twist barrel, with a BC of .500

Here's my experience with them so far: viewtopic.php?f=3&t=7221

I really need to get my Sako shooting consistently so I can continue load development.
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Re: Anyone bedded a Sako 85?

Post by Apollo » 21 Dec 2016, 11:01 pm

My Berger bullets cost less han $60 / 100 even cheaper since I buy in 500-1000 lots and I'm now starting to wonder if some of your problems are bullet weight too high / too long as you don't have a heavy varmint barrel even though the twist rate is a touch faster...maybe. The "flyer" may be instability... ??
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Re: Anyone bedded a Sako 85?

Post by Gwion » 22 Dec 2016, 7:36 am

All that wear on the bedding is saying bad things. Something is definitely interferring with a clean battery.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 22 Dec 2016, 7:45 am

The 100gr Game Kings are designed for standard 10 twist barrels, but I'm seeing the same pattern with factory ammo - 80gr Federal SP (first photo in this thread) and 95gr Winchester BST.

The TMKs are shooting OK when the rifle behaves itself, with decent groups at 40.0gr and 40.5gr of 2209. Things started to spread out at 41gr, and you can see that typical top-left flyer at 41.5gr, but the group got tight again at 42.5 (not pictured). 43.5 shows another typical flyer and 44 - which is quite a hot load - is still 1MOA.

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Also, compare the Game King 39.5 in the first group I posted above to the same load a few days later (below). That is an accurate load, and again you can see that top-left flyer. I have lots of groups with factory ammo like this: 3-4 nicely grouped shots with one random flyer to the top left, or double groups top-left/bottom-right. I saw this same type of grouping pattern when I had bedding problems with my CZ527 before I fixed it (I did a poor bedding job the first time and had to redo it - it now shoots really well)

The gun is definitely moving around in its stock, and you can sometimes see it move from left to right in the the channel after a particularly poor group.

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Re: Anyone bedded a Sako 85?

Post by Flyer » 22 Dec 2016, 3:49 pm

OK, for the record (after a phone call to clarify things) we've established the Sako tang washer isn't embedded in the stock and may be a shim added at the factory to correct discrepancies in rear stock height to keep the action level.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 14 Jan 2017, 4:11 pm

So now we're getting somewhere. I made up a stainless steel pillar for the rear action using 8mmx1mm tubing, which has a slight interference fit with the rear screw hole (it fits nice and snuggly). Here's what it looks like:
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Fitted to the stock, you can see how the pillar supports the rear action screw housing, which doesn't touch the wood - only the rear tang (upper level) touches the wood).
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To make the pillar, I first had to cut it over-length and fit it, then put some plasticine under the rear tang to see how much more I needed to shave off (about .030" initially). Once the plasticine indicated the tang was touching the wood with the pillar in place, I then had to shave a few thousandths of an inch off at a time so that the rear tang had good contact with the wood (slight compression) with the pillar holding the action in place. This way, the rear tang (action) is not being held off the stock by the pillar when tightened up.

Once I bed the rear tang properly with Devcon, it will set at precisely the right height - this is just a trial run for now to see how it works without having to alter the stock.
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You can see the underside of the pillar flush with the trigger guard housing. Once the action is held in place, you can turn the rifle over to see if the pillar is too long or short by where it protrudes through the trigger guard.
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You can also see from this photo that the rear action hole is drilled off-centre (towards the left in this photo, but towards the right of the stock as you hold it). The importance of this will be explained in a minute . . .
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Re: Anyone bedded a Sako 85?

Post by Flyer » 14 Jan 2017, 4:15 pm

The groups were not astounding, however, there were no fliers throughout the range test - which is what I was looking for. Most groups were around 1moa, such as this.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 14 Jan 2017, 4:27 pm

This is where things get interesting . . . After pulling the rifle apart again, I discovered safety screw had left an imprint on the stock where it was hitting. It is the dent in the middle of the half-moon shape in this pic. This cannot be good for accuracy and I can't believe it took me this long to see it.
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There are possibly three reasons why the safety screw is hitting the stock

1) not enough clearance;
2) the rear action is moving around;
3) the safety screw itself is defective and sticking out too much.

I discovered it was probably a combination of all three. Have a look at the screw - there is a shank between the thread and the step where the screw seats against the trigger. You can see when properly screwed in, only a few threads hold the screw in place. On my rife, the screw was sticking out. It seems like a defective screw.

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I will either need to find another screw, or use a dab of Devcon around the shank to create more threads to ensure the screw stays in place once tightened into position.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 14 Jan 2017, 4:40 pm

With the rear action sorted (at least, with most issues discovered), it was time to look at the front action. A friend of mine let me pull his new (12 months old) Sako 85 Bavarian apart and I discovered it had a different recoil plate to mine.

This is what mine looks like:
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And this is the other design - which is much stronger and more stable (not my friend's rifle, but the same type of recoil plate):
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It is difficult to see in the photo below, but my recoil plate is see-sawing and moving around on the stock - you can see faint impressions of where it has been moving around. Clearly I need to get a new-design recoil plate and bed it properly in the stock.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 14 Jan 2017, 8:44 pm

First mod: deepening the safety screw hole/recess so it doesn't bottom out anymore. Shiny stuff is new wood sealant. I also put a little dab of Devcon on the safety screw thread and snugged it into place. I'll put the rifle back together without the rear pillar, initially, to see if clearancing the safety screw makes any difference. Always best to eliminate one possible bedding issue at a time until the problem is narrowed down.
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Re: Anyone bedded a Sako 85?

Post by Gwion » 15 Jan 2017, 8:05 am

Good to see some progress. Watching with interest in case I came one day afford one of these for a hunting rifle.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 16 Jan 2017, 1:04 am

Hit the range today. Shot without the rear pillar in place and the rifle double grouped again. I put a little extra torque on the rear screw, too (40inlb), which didn't seem to make much difference:
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I also noticed the barrel had moved in the stock, from the centre of the barrel channel to the left, after shooting a few rounds through it:
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As soon as I replaced the pillar, the rifle started shooting a lot more consistently. All groups were at 100m:
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No doubt, the rifle needs to be bedded to stop it moving around. That will be my next project, but I will need to wait until I have the new recoil plate first. At least I seem to have nailed the problem.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 13 Mar 2017, 6:43 pm

The rear pillar on mine is 29.5mm - but exact pillar lengths will vary (slightly) with each stock. I machined it from stainless tubing, as that's what was easiest to find ($9 on eBay), and the 8mm OD capillary tubing I used was the exact size for the 8mm screw hole to fit. I determined the length by removing the trigger guard, and pushing a length of 8mm tubing into the action screw hole until it hit the action, then cutting it slightly oversize (31mm), and rubbing the ends back with 320-400 wet and dry until I got the correct length.

I have not pillared the front, but I have bought a new recoil plate which I have now bedded. I'm also in the process - after lots of trial and error - of fully bedding the rifle (over the recoil plate).

Bedding the front recoil plate made almost no difference, but stabilising the rear with the pillar did remove the fliers, and got some of my 4-shot groups down to about .750" at 100m. Bedding the front should improve consistency. I'll post everything up soon.

On a side note, my 85 is an older rifle that had been in someone's safe for a long time with very little use (hence looked new, but was 6-7 years old). Whether, over time, that had affected the stock so that mine didn't sit right is a distinct possibility, as I have seen a couple of new 85s that shot great straight out of the box - including a 243 varmint laminate using factory ammo (Winchester Ballistic Silver Tip 55gr and 95gr both seem to work nicely, as well as Federal 80g Power Shok).

If I were you, I'd go out and shoot it and see what it's like - it could well surprise you. And, being a new rifle under warranty (and five-shot 1 MOA guarantee), if it doesn't shoot great out of the box, I'd return it. The only reason I am going through all this is because mine was second-hand, quite a few years old, and I wasn't in a position to return it to the factory.
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Re: Anyone bedded a Sako 85?

Post by Apollo » 13 Mar 2017, 8:10 pm

Boy, I really hope you solve this drama. I hope in some way what we have discussed will have helped.

I have not shot a calibre rifle Sako or not of what you have so I don't know but in saying that any Sako I have shot say .243W and below has always produced sub 1//2 MOA results.

I feel for you.
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Re: Anyone bedded a Sako 85?

Post by Flyer » 14 Mar 2017, 12:15 am

We'll find out soon enough. I've just finished bedding it tonight and will pull it apart tomorrow to see how it looks. I left the recoil plate in, and plasticined the redundant recoil lug hole (the one they used with a floating recoil lug system in the Sako 75s and Tikka T3s), so that it doesn't create another recoil point like your .243 laminate (the one bedded by the gunsmith that uses an epoxy/Devcon recoil lug). I've also only bedded under the tang - not both levels of the rear (around the rear action screw) like your .243. I can always bed the bottom part later if I feel the need.

Apart from that, I used your .243 as a guide - so that's been very helpful. I decided to pull the trigger (so to speak) and properly bed it because I figured the way it sits in the stock now is obviously the problem, and the pillar I machined is really only a temporary measure. The action really needs to be bedded front and back so that it can't move around in the stock.

In my favour at least is that the rifle shoots pretty consistently with the rear stabilised. Below are a couple of groups I shot yesterday, and they both measure under .900". Nothing outstanding (there was a bit of wind about), but OK for a sporter barrel and at least no more fliers.

I also take heart in the fact that, whoever had your .243 before you bought it obviously felt the need to have it bedded, and that after bedding it seems to shoot really well. Which is to say, Sako's own bedding system clearly isn't perfect.

CCI13032017.jpg
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Re: Anyone bedded a Sako 85?

Post by Apollo » 14 Mar 2017, 1:02 am

I wish I had kept my last target from what was going to be a test day for load development.

1st fouling loads produced 4 in one hole and the 5th shot just touching at 100m so, just as we moved targets to 300m the wind plus mirage turned up. End of testing as it would not have been worth wasting barrel wear. I actually think the one out of the single hole may have been the first cold shot.

It was a busy day as I had 100 220Russian cases to fireform into 6mmPPC so I was swapping rifles every few minutes.

BTW, I was really impressed with the 6mmPPC even though this was just 100m Fireforming. A number of sub 1/4 MOA groups so I'm keen to see how it goes at competition which will be 100 & 200 Yards. Fireforming was from just a very old hand me down worn out 18" barrel that was a gift.
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Re: Anyone bedded a Sako 85?

Post by Apollo » 14 Mar 2017, 1:06 am

Opps, I forgot you have a .243W... but it's a Barvarian with a light profile barrel.

Sorry, I keep thinking it's a higher calibre....

I'm getting too, too old.....
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Re: Anyone bedded a Sako 85?

Post by Flyer » 21 Mar 2017, 7:46 pm

Well I hope this helps someone, because this whole episode has been doing my head in!

However, there is light at the end of the tunnel, and it turns out all my problems could be down to one loose screw . . .

First thing's first: I replaced the front recoil plate with the new/old design. I say "new/old" because I have seen this recoil plate on both new and old original Sako 85s, but somewhere in the middle they changed the design and then went back. The dimensions that count (thickness, width, screw hole placement etc) are exactly the same. They are also the same (interchangeable) throughout the Sako 85 range, from XS to S, SM, M and L actions.

Recoil.jpg
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Original recoil plate left, and the new one I bought from Beretta right.

RecoilNew.jpg
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New recoil plate

RecoilOld.jpg
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Old recoil plate

I then set about bedding the rifle. First, I bedded the recoil plate into the stock so that it was level and would not move in the channel. I used masking tape on three sides of the receiver lug - front and sides - that fits into the square hole at the rear of the recoil plate so that the rifle action sat level, with the rear of the receiver lug making contact with the recoil plate. I used masking tape around the barrel to centre it in the channel, then tipped the rifle on its stock and tapped it on the ground to settle recoil plate, lug and receiver at their rear-most point to ensure proper battery. I then torqued the rifle down so the action screws were nipped up front and back.

After bedding the recoil plate, I then bedded the action and rear tang. I also redrilled the rear action screw hole and centred it in the stock using 8mm tube and bedding compound.

Bedding.jpg
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You can see where I have bedded over the recoil plate. My main concern with this is that the recoil plate is made of steel and the bedding compound is mostly aluminium (Devcon). If the steel expands when it heats up, there is the possibility it could rise and dislodge the bedding compound. However, after shooting the rifle and pulling the action out of the stock when hot, I've discovered the recoil plate does not heat up much and so far there are no signs of disturbance.

I also plugged the action with plasticine where the old floating recoil lug would have gone (same as the Sako 75s and Tikkas). You can see a couple of rough patches either side of the bedding compound where I have plugged the gap.

Yes, I have a plan "B". If the bedding compound is compromised in any way, I will simply remove it from the recoil plate and leave the remainder attached to the stock (the bits on either side) to keep the action centred. The recoil plate is where the action beds to the bottom of the rifle - the bedding compound along each side of the inner stock simply keeps it centred during assembly and battery.

Tang.jpg
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I only bedded under the rear tang, and not the lower level (I can always do this later). Like the recoil plate, I left some wood untouched as a guide, then removed some wood around it with the Dremel and bedded the bottom, sides and rear of the tang. After bedding, I clearanced a very small amount of bedding compound around the very rear of the tang to prevent the tang hitting it under battery and chipping the wooden stock. I needn't have bothered, as I discovered the action is now rock-solidly bedded in the stock and does not move at all when the action screws are tightened and loosened.

So, did this make any difference to the way my rifle shot?

No. And yes.

My first five shots were all over the place. The bedding had made absolutely no difference at all. I was dumbfounded! So I tried my old trick again, and put the stainless steel pillar back in the rear of the rifle and tightened both front and rear screws to 6nm.

Vmax.jpg
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I could not believe it. The first shot went 1/4" low at 100m. The next two shots went into the same hole, just above. I loaded a fourth round and it, too, went into the same hole. That's a .150" three-shot group opening to .400" with the first shot. This is the best group I have shot so far with the rifle, and the bedding does seem to have worked. It certainly hasn't hurt. This was with my 87gr V-max load of 44.5gr of 2209 chronoed at about 3300fps.

VmaxGroup.jpg
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So I pulled out another accuracy round, 100gr Game Kings with 39.5gr of 2209 at about 3000fps. The first shot was pulled after the guy next to me let off his 243 just as I pulled the trigger and jumped out of my seat. The next two shots went into the same place as the Vmax (almost the same hole). The third shot was a little lower. Everything seems OK . . .

GameKing.jpg
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The next group is when things started to fall apart. Two shots into the same hole 2" above the target - same as the others, then two very wayward shots low and left-right.

Just out of curiosity, I got my torque wrench out and put it on the rear action screw - it was loose.

I have noticed that each time I shoot the rifle without the steel pillar, it's all over the place. As soon as I put the pillar in and torque it down, the rifle shoots dead-straight. I was seeing a pattern developing . . .

When I first got the rifle, it shot really well. But then I noticed the action rattling around in the stock. When I pulled the action screws out, I found remnants of thread locker on the action screws and thought nothing of it. This oversight is what has probably cause me all my grief.

What I have learned in all this is that the stainless steel pillar not only helps stabilise the rear of the rifle, but it allows me to torque the rifle up tight without putting too much pressure on the wooden stock. Without the pillar, the rear action does not like to be too tight in the stock (the more you tighten it, the more groups spread). However, with the correct torque - and no locking compound on the threads - the screw simply works its way loose after a few shots and shoots like a pig. With the steel pillar in, you can tighten it with the correct tension on the stock, but it also stays in place longer (but eventually it, too, vibrates loose).

So what to do? I just bought some Loctite :lol: The next stage may be to bed the stainless steel pillar into the stock and simply leave it there and Loctite the action screws into place and be done with it.

If my rifle shoots consistently after all that, I will have reached a number of conclusions:

1) The Sako 85 bedding system works well - when it works
2) Bedding a Sako 85 does not seem to hurt it, and may even improve it marginally
3) So far, bedding over the recoil plate (as long as the recoil plate is bedded first) seems to be OK
4) Sako 85s do not like a lot of tension (screw torque) on the rear action!
5) For reason 4, pillar bedding is a good idea
6) Thread locker!

I may need to examine the threads on my action screws and the action itself to determine if they are flawed, but considering the whole thing is only held in by a few threads anyway, thread locker (Loctite) simply makes sense.

I hope others can learn from my mistakes and that this has all not been a terrible waste of time! I will report back with more results in due course.
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Re: Anyone bedded a Sako 85?

Post by Chronos » 22 Mar 2017, 7:11 pm

Have a mate with a 85 in .308, action screws often come loose as well. We do like to mock him with a little "rattle rattle" tease from time to time which started on a hunt when he shook the gun and the action rattled in the stock :lol:

Hope you finally have it sorted mate, Chronos
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