Before I go into the details I want to put foreward something strange I have noticed.
I have seen many firearms accidents occuring in other peoples hands. Personally, touch wood, I have never had a round get away from me unintentionally.
However, I have seen people do strange things even with my own rifles and caused them to go off unexpectedly.

Today a friend was unloaded a Sako 75 after having lined up a fox that never presented a shot. He had put the rifle on safe while he took aim and before unloading it he slowly slid the safety off, and teh rifle went BANG!

I was watching him, he's new to guns but I could clearly see his hand was no where near the trigger guard as I had always instructed him.
I tried to replicate the event and couldn't get the gun to go off. Slamming the bolt, slamming the trigger - I'd pass the empty rifle back to him, and he'd make it go off. Then I noticed he was pressing down pretty hard on the safety while sliding it foreward. It turned out that even without moving the safety you could make the hammer drop.

This is quite disturbing to see, although I have never been a big fan of using a safety anyway so I always keep the rifle unloaded until I need to shoot.

I have shot literally hundreds of animals and maybe 5000 rounds at paper through this rifle and never caused it to go off.

Does anyone have any idea what the problem might be here?

On an empty chamber, put the safety in the on position, pull the trigger, remove your finger and slide the safety off and see what it does. If the striker falls, then the sear is sitting too close to the edge and safety is not able to block the trigger levers movement. I am trying to picture the trigger to see what adjustments you have available. I will try to look it up and in the mean time maybe you can do the above test.

Good and fine Westpac, it passes that test.
What I'v said happens is that if you push downwards, not forewrds on the safety, it will dropthe hammer. As if it were a second trigger.

Just a little thinking out loud here...

I am not familiar with that safety/trigger/sear arrangement of that model
Sako, but it sounds as if one or more of several things might be happening:

Is the tang bedded sufficiently well that it cannot flex when one pushes down on the safety? one of the tests for Remington trigger sear engagement is to whack the rear of the tang with a hammer, when the rifle is cocked. Presumably the "whack" will temporarily flex the tang and allow the striker to fall if there is insufficient sear engagement. Maybe something similar is happening here if the tang is flexing under heavy pressure applied to the safety?

Or, how tightly mounted to the action are the trigger/sear/ and safety...i/e. How good a fit are the pins, etc.? Is it possible that pushing down hard on the safety causes it to engage either the sear or the trigger just enough to move them out of their proper relationships to each other and/or the cocking piece?

Have you tried removing the barreled action from the stock and watching all the various firing mechanism parts as you press down hard on the safety with the rifle cocked (and UNLOADED, of course)?

Sounds as if something is changing its orientation and location due to the pressure applied to the safety. Hopefully, it will be possible to find that by close observation of the process.

Either your freind had his finger on the trigger or your Model 75 is Broken.
I went and tried what you described on 4 different Sako Model 75's and couldn't get a single one to drop the hammer. I pushed down on the safety's with considerable force while working them back and forth and also while hitting the bolt release lever.
If your Model 75 ever goes off while working the safety something is broken......................DJ

I worked on a few 22 pistols including my own Browning Challenger years back ,that had the same problem .Loaded ,safety on,pull trigger - nothing happens . But when you then disengage safety the gun fires.It then requires very careful work [from a knowledgeble smith] to correct

quote:

Originally posted by djpaintles:
Either your freind had his finger on the trigger or your Model 75 is Broken.
I went and tried what you described on 4 different Sako Model 75's and couldn't get a single one to drop the hammer. I pushed down on the safety's with considerable force while working them back and forth and also while hitting the bolt release lever.
If your Model 75 ever goes off while working the safety something is broken......................DJ

+1, except I tried it on 15 different 75's!

I've got a Sako whose safety lever is stuck.I never had this happen with any other rifle.