Winchester 70 Accidental Discharge

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Nachoninja

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Hey everybody, I have a Winchester Model 70 Stealth, 2nd owner but basically mint, fired very little. It has "Baco Inc, Morgan Utah" written on the barrel so I assume it's one of the new FN produced models. Anyways, took it out shooting on the weekend for the first time, was shooting under 2 inch groups at 200 yards with factory ammo, so I was very pleased. However, first time I put the safety on (all the way to full safe position) and flipped it off the gun fired. Never touched the trigger. I was quite shocked, tried it a bunch more times with the chamber empty, probably 50% of the time if I flipped the safety from full safe to fire the trigger would activate. My immediate thought was that someone adjusted the trigger too light, because the same thing would happen with a CZ-527 I have when I adjusted the trigger way too light. However, the trigger pull was nice but nowhere near where I thought it would be unsafe.

Anyways, went home, took the gun apart, saw that the trigger is one of the new M.O.A. models on the new Winchester 70's, and is therefore easily adjusted according to the manual. I turned the correct screw to increase the trigger pull weight until the trigger basically would not pull when everything was put back together, then I backed it off slightly, put it together and tested the safety again. When the trigger was adjusted to this position and I cocked the bolt and tried the safety it seemed much improved. The trigger would not go off if I flipped the safety from the mid point to fire, but about one in 10 times if I flipped the safety from full on to fire with a bit of force the trigger would go off. This is about as heavy as I can adjust the trigger, and still the gun will discharge occasionally if I flip the safety off. I readjusted the trigger back to something reasonable and now it will discharge maybe 1 in 5 times.

I've been trying to find similar occurrences on the internet but all I can find is instances of the Remington 700 doing similar things, never the Model 70. Anybody know what could be going on or of a Winchester warranty center in Canada or gunsmith that specializes in Model 70's? Thanks
 
Is the trigger assembly completely clean? Some gun owners seem to think that they need to soak the living hell out of every part with all sorts of oils, grease, solvents, coatings etc. Often internal parts will have a coating of dried lubricant and dust, creatin a sort of varnish. This can cause problems like this.

Another possibility is that someone has tried filing/honing the sear.

If it doesn't sort itself out shortly, I would buy a replacement trigger (and) assembly. These are usually pretty straight forward to install, and can be done without a gunsmith. It is not worth taking a chance on.


Cheers.
 
I would assume the trigger assembly is fairly clean. The new M.O.A triggers assemblies are completely contained, so hard to see in side of them, but the rest of the gun was perfectly clean so I doubt there's a lot of gunk in the trigger. I'm not sure how to get it further apart to check.
 
x2 on contacting winchester, Thats where Id start. Then maybe a good gunsmith if winchester cant help you. Hopefully someone on here can recomend a good one for you. Definatly something you want to get sorted out.
 
When a model 70 safety swings back, a half cylinder engages a ramp on the firing pin/cocking piece and retracts it off the sear.

When it it released, it dumps it forward onto the sear.

Because the problem is intermittent and decreases with return spring pressure, the problem is likely the sear to trigger contact rather than the sear to cocking piece contact.

Try this: #### the rifle and engage the safety while pushing the trigger lever forward with your thumb and then flick the safety off. Do this a few times, and if the firing pin does not fall, then the problem is likely dirt causing the trigger lever to stick and fail to reset

If you can duplicate the failure with the trigger pushed forward, then either the sear is not rising high enough, or is faulty in dimension.
 
Thanks, I will try this tonight. Just to clarify, I hold the trigger forward the whole time, or just when I engage the safety?

rgv said:
When a model 70 safety swings back, a half cylinder engages a ramp on the firing pin/cocking piece and retracts it off the sear.

When it it released, it dumps it forward onto the sear.

Because the problem is intermittent and decreases with return spring pressure, the problem is likely the sear to trigger contact rather than the sear to cocking piece contact.

Try this: #### the rifle and engage the safety while pushing the trigger lever forward with your thumb and then flick the safety off. Do this a few times, and if the firing pin does not fall, then the problem is likely dirt causing the trigger lever to stick and fail to reset

If you can duplicate the failure with the trigger pushed forward, then either the sear is not rising high enough, or is faulty in dimension.
Click to expand...
 
rgv said:
When a model 70 safety swings back, a half cylinder engages a ramp on the firing pin/cocking piece and retracts it off the sear.

When it it released, it dumps it forward onto the sear.

Because the problem is intermittent and decreases with return spring pressure, the problem is likely the sear to trigger contact rather than the sear to cocking piece contact.

Try this: #### the rifle and engage the safety while pushing the trigger lever forward with your thumb and then flick the safety off. Do this a few times, and if the firing pin does not fall, then the problem is likely dirt causing the trigger lever to stick and fail to reset

If you can duplicate the failure with the trigger pushed forward, then either the sear is not rising high enough, or is faulty in dimension.
Click to expand...

Best advise.
 
Nachoninja said:
So it still happens if i hold the trigger forward the whole time, so definitely a problem with the sear
Click to expand...

Never being afraid to admit I was wrong, I was wrong.

moa_trigger_cutaway.jpg


Because you were able to decrease the frequency of the failure by increasing pull weight, I am 99% certain that it is the intermediate lever (which I forgot existed) that is not 're-setting', probably due to dirt or other contamination.

It is only partly engaging the sear, and when the safety is released and the cocking piece slams forward onto the sear, there is not enough positive engagement to stop it.
 
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