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L579 Cocking Issue

Sako Collectors Club Discussion Forum

Bottom Gun

Well-Known Member
Yesterday was the last day of our deer season. I had a point blank shot at a nice three point buck standing at about 40 yd. I chambered a round but the bolt would not stay cocked. I opened and closed the bolt repeatedly but the rifle would not cock.
The buck finally tired of watching me struggle to shoot it and trotted away. It was nearly sundown so my hunt was over.

I was using my ‘60s vintage L579 Deluxe in .243. It’s an older model with a flat bolt handle, half moon catch and slanted fore end, serno 149XX.

This morning I took the rifle apart to examine it. I thought the trigger adjustment screw might have loosened but it hadn’t. The adjustment screw and lock nut are still tight. Every fastener I checked is tight.

Now, with the action out of the stock, the rifle cocks and trigger works again and is still set at the 3 lb weight I adjusted it for long ago. I put the action back into the stock and everything works fine again. The safety works and moves easily. It doesn’t appear to rub anything.

Some history: This was a used rifle I bought through Gunbroker a few years ago. It had seen some very rough handling and looked like the former owner had parachuted into his last hunt with it. So, it’s a great shooter but not a real collectible due to cosmetic damage.
It had this problem of not staying cocked when I first received it but the issue was intermittent. I noticed the trigger adjustment screw and nut were loose. I readjusted the trigger weight and it worked perfectly for well over 100 rd. I mistakenly thought I had fixed the problem.

The rifle had been riding in a case on my UTV all week so it experienced some vibration and occasional jarring but nothing really severe.

So, I’m trying to figure out what this problem is and how to fix it. I’m tempted to replace it with a Timney trigger but would like to try to correct this issue before I start adding aftermarket parts. Does anyone have an idea as to what might be going on with this trigger?

I see a factory Sako trigger is available from Custom Shop, Inc. in Hamilton, Montana. Has anyone had any experience with these?

Does anyone have any ideas or suggestions they would like to share? DSC_0553.JPG DSC_0600.JPG

Thanks in advance.
 
First off I will say this. The trigger may or may not be the culprit but the trigger you buy from that shop will be too expensive and it may not work. The older flat bolts have a trigger that is thin and the new ones may not fit the slot in the trigger guard. For what that trigger would cost you, you can very easily afford a trip to a reputable smith. He can clean it and adjust to the proper levels of performance. If you don't have access to a good smith, please use the PM system and get ahold of me. Good luck. I can ALSO SEE that the trigger is not sitting in the guard correctly. You may only need to adjust the housing level but a smith is your best bet.
 
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I can tell just by looking that your trigger is gunked up inside & is not allowing the sear in the trigger to rise into position to catch the bolt sear. The harden oil on the outside is the give away. This is spring powered & the harden gunk is making that part stick. Take the trigger off the action by loosening the lock nut and unscrewing the screw most forward in the housing & driving the pin just behind that screw out. If you don't feel comfortable disassembling the trigger, just drop it in some lacquer thinner for a couple days, then flush all the gunk out with some of that aerosol gunscrubber stuff, followed by some compressed air. Flush till it all comes out clean. Might take a couple soakings. Of course, the best way is to disassemble the trigger & clean all the parts & springs. If you are halfway mechanical it's not that hard, but do be very careful as there are springs inside, as well as a detent ball on the safety lever that if dropped may be a nightmare to find. Just taking the trigger lever out alone helps with the flushing method by giving better access to the sear & spring. Good luck!
 
Paulson is dead on. I had a similar problem a few years ago with an early L61R and it was exactly as he says - gunk in the trigger mechanism. I went ahead and took it apart and cleaned it out and now it's fine. I also second what Paulson says about tiny parts, the safety detent ball, etc. If you're going to do this one yourself, you need a clean, open workbench and the right tools and solvents. Only you know your skill level, act accordingly. Another possible option would be to drop the trigger assembly in an ultrasonic cleaner for as long as necessary, dry it with a hair dryer, and then squirt some CLP into it (ultrasonic cleaning solutions are usually water based). That would most likely work, but disassembly is still the best.
 
Thanks for your helpful information, everyone. I truly appreciate it.

I’ll start by playing safe and soaking in some solvent. I don’t have any lacquer thinner but I do have acetone, carb cleaner & Seafoam. I was thinking about trying some Marvel Mystery Oil after I saw how well it cleaned some other parts.
If necessary, I do have an ultrasonic cleaner as well.

Does it matter which direction the pin is driven out?
 
Thanks for your helpful information, everyone. I truly appreciate it.

I’ll start by playing safe and soaking in some solvent. I don’t have any lacquer thinner but I do have acetone, carb cleaner & Seafoam. I was thinking about trying some Marvel Mystery Oil after I saw how well it cleaned some other parts.
If necessary, I do have an ultrasonic cleaner as well.

Does it matter which direction the pin is driven out?
Once the screw is loosened the pin will push out very easily. Either direction is OK! Acetone or carb cleaner will work well, also. I have no experience with ultrasonic cleaners. Mystery Oil is more suited to freeing rusted parts from my experience & if not cleaned out can result in the same problem. Wouldn't hurt to try it though!
 
So far so good. I have the trigger assembly soaking in acetone. I think you guys are right about it being gummed up. Even the nut and screw forward of the pin had to be broken loose as if they had tread locker but there was no evidence of any so it must have been solidified oil binding them.
I’ll save the Marvel Mystery Oil for what it’s intended. I have to admit though to being impressed by the way it made my grungy measuring cup sparkle when I poured some into it.

Can I assume that screw with lock nut is what levels the assembly? Is the setting critical? Is there a way to determine if it is set correctly or do I just eyeball it?
I did notice that forward screw was turned in quite a ways. That could be why the trigger looked a bit far aft and low in the trigger guard. I’ll try a bit less screw when I reassemble it and see how that looks.

I’ll soak it for a couple of days and then put some CLP into it. Hopefully, that will do the trick. I would like to get this old guy back into action. It’s my last deluxe Sako. I had to part with my others (in larger calibers) after my shoulder replacement. Doctors can sometimes be cruel despite the oath they take.

I’ll let you guys know how this all shakes out. Again, I truly appreciate the guidance you guys have given. You may have saved me from having to do some world class cussing since I had no idea trigger widths changed or some of the other items you mentioned.

I’m trying to fix this myself because I don’t know of any gunsmiths nearby I would ask to work on one of my Sako rifles. I live in the country just a stone’s throw from the border so nothing is really convenient. Please don’t misunderstand, I’m not complaining. It’s the price one pays for the lifestyle and well worth it.
As far as shipping, after having several rifles damaged in shipment, I’m reluctant to ship unless as a last resort.
So, with your help, we’ll get ‘er done right here. One of things I enjoy about guns and shooting is that I never stop learning about them.

Thanks !!!!!!!
 
The trigger attachment screw uses leverage to hold the trigger to the action. Tighten it up solidly, then use the lock nut to insure it won't come loose. It has no affect on how the trigger "sits in the trigger guard". If it is not seated all the way & tight, you are asking for trouble. There is no "setting" & it "levels" nothing. Scares me to death what some people do with guns. I should have just told you to take it to a gunsmith. You obviously don't have any concept of how things work with this trigger system or it's mecahnics & are overthinking things, so step back & give some thought to what you are about to do. You don't just "eyeball it" for crying out loud!!!! This is not a game. If you screw it up someone could get hurt or KILLED!! There are threads here & on-line that can explain things in more detail. If you can't educate yourself to confidently do this work, get it to someone who can.
 
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Bottom Gun when you put the trigger back in place make sure the pin is properly in place and snug the forward screw until the trigger will not rock forward or aft then 1/4 turn or so to finish. There should not be any looseness at all in the mount. Tighten the nut and you're done.
 
Gents,

We've not addressed the trigger leveling adjustment screw, that is on top of the trigger housing. You must remove the entire trigger assembly, from the receiver, in order to see and adjust it.

It's normal position is such that the top of the housing will be "level" with the underside of the receiver......when the trigger assembly attaching screw & nut are fully tightened.
This will probably require some back & forth assembly and dis-assembly, in order to get the tiny top adjustment screw position correct. I usually adjust the tiny positioning screw only 1/8th turn at a time.

BTW.....when attaching/removing the trigger assembly from the receiver.....position the lock nut at the TOP of the slotted screw, to prevent possible splitting of the screw slot while tightening or loosening the anchoring screw. Spin the lock nut down, to it's tightened position when finished.

Hope this helps.
 
We've not addressed the trigger leveling adjustment screw, that is on top of the trigger housing. You must remove the entire trigger assembly, from the receiver, in order to see and adjust it.
Not all Sako #4 triggers had the leveling screw, however most of the older ones like this one did have such screws.

Importantly, this screw controls the degree of engagement of the cocking piece sear and if such engagement is inadequate the firing pin can drop prematurely, or even fail to cock as the poster has experienced. Raising the screw (counterclockwise) decreases the engagement and lowering the screw (clockwise) increases the engagement. It is possible that some previous owner has adjusted the screw so that the sear engagement is inadequate.

In later years Sako chose to do away with this adjustment screw. It was probably incorporated in the first place to allow for the variations in receivers of the actions made by other manufacturers for which Sako furnished its triggers. Sako apparently found that if fitted only to their own receivers that a fixed sear engagement was both consistent and adequate, thus they dropped the engagement screw and negated the problem of improper adjustment by shade tree gunsmiths (and, unfortunately, some people who call themselves gunsmiths and charge for their services pretty much operate under shade trees.)
 
Yep......

The newer #4 Sako factory triggers have replaced the small positioning screw with a raised boss on the trigger housing itself.

I'm pretty sure this is the case for all "A" series actions......but may also include later production "L" series.
 
Hi Mr. Bottom Gun,
If you go to the main page & page down, find the "Gunsmithing Tips" heading.& see Tilleyman's post on # 4 triggers . I think this may be the tech. data you need to fix your problem once you get the trigger assy. cleaned as our fellow members have suggested. These triggers are quite good if properly cared for. It is true that the Timney triggers are narrower as I have replaced a #4 trigger in a Mark 4 Interarms .243. Best of luck !
B/T
 
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Perfect. Thank you for the link, Bucktote. That post is a wealth of information. Exactly what I was looking for.

That clears up my misunderstanding of the comments regarding the “grub” screw referenced by dimension AA in the first illustration in that post.
Turns out this trigger has a standoff instead.

I’m surprised at the amount of residue that is coming out of this trigger. Must be 60 yr of crud.
 
Bottom Gun,

As old as this trigger assembly is, there should be a level adjustment screw on top of the trigger housing.

Would you post a picture of the "standoff" you mention?
 
Thanks for the extra pics.

Can you tell how it attaches to the housing? Screwed in? Slip fit?

I've never seen such a thing on a #4 trigger housing.
Anyone else?
 
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