Zastava M85 firing pin light strikes

[DGP4]

I meant the front half of the extractor with the circular nub.

 

[DShortt]

So I finally made it to the range after fixing the bottom metal bedding. And encountered the same problem.

Spent some time fiddling around checking things like making sure the safety was not moving during firing. And I discovered that after fully closing the bolt if I rotated the bolt handle ever so slightly toward open that the rifle fires every time.

So next I need to investigate what is happening with the bolt, but at least I know what is causing the light pin strikes.

 

[DGP4]

IIRC, The firing pin is threaded into the cocking piece and fixed with a set screw. Maybe you should check to see if the screw is loose or has been bent,

 

[matthias]

Also need to check the opposite side of the cooking notch and see if it making contact , adjust as required.

 

[DShortt]

Also need to check the opposite side of the cooking notch and see if it making contact , adjust as required.

I'll be cleaning it later today. Just put some Ed's Red in the bore at the range before I left to keep any deposits soft and temporarily prevent corrosion. Thanks for the suggestion.

 

[DShortt]

So I've got the bolt and rifle on the bench and I can't decide what is going on here. I don't see anything anywhere that indicates something is restricting firing pin fall. The only thing I see that might explain it is if the sear is contacting the bolt body but I don't see any contact marks.
Not sure what to do at this point and I don't want to start making any adjustments without knowing what I'm trying to accomplish.

 

[AlNyhus]

Have you adjusted the trigger to factory specs?

 

[DShortt]

As a picture is worth a thousand words. The possible contact point I'm wondering about is that corner right near the pick point. The firing pin is fully forward right now. When retracted the sear is rearward of that corner and *might* be hitting it when passing by?

 

[DShortt]

Picture isn't the greatest. Best I can do.

 

[Sniperhandle]

View attachment 1498309As a picture is worth a thousand words. The possible contact point I'm wondering about is that corner right near the pick point. The firing pin is fully forward right now. When retracted the sear is rearward of that corner and *might* be hitting it when passing by?

In your pic on the right side of the shroud is what is called the "Bayonet" The small pin inside of the window should be bottomed out against the front, Or top of the window in the pic. Take the Bayo out and clean it. All you have to do is depress the front of it and use a pick to move it out of the window. You would need to remove the shroud from the bolt first.

Make sure the bayo is not galled or has burrs on it and also the bore for the bayo.

I could be wrong about this because I am going off of the way the Bayo sits in a Mauser shroud, But why would they make the window that large if it wasn't supposed to be up against it like the Mauser?

Pics from web of Mauser 98 bolt.

 

[DShortt]

In your pic on the right side of the shroud is what is called the "Bayonet" The small pin inside of the window should be bottomed out against the front, Or top of the window in the pic. Take the Bayo out and clean it. All you have to do is depress the front of it and use a pick to move it out of the window. You would need to remove the shroud from the bolt first.

Make sure the bayo is not galled or has burrs on it and also the bore for the bayo.

I could be wrong about this because I am going off of the way the Bayo sits in a Mauser shroud, But why would they make the window that large if it wasn't supposed to be up against it like the Mauser?

Pics from web of Mauser 98 bolt.
View attachment 1498351
View attachment 1498352

I understand what you are describing. What I don't understand is how that would affect firing pin travel? Particularly since that pin is pushed further rearward when the bolt is closed?

 

[DShortt]

Also, when the shroud is rotated to the bolt open position, the bayonet fits into a notch in the bolt and the bayonet fully extends. Like this.

 

[DShortt]

So after considering this a bit, I wonder if the bolt is actually rotating a bit too far when fully closed and allowing the sear to to contact the bolt body just enough bump off the body and to reduce the pin velocity when the trigger is pulled.

Never saw that before but I'm no Mauser expert for certain. I presume that the bolt lugs normally determine when the bolt rotation stops when fully closed. Perhaps this one is off just a tad?

 

[AlNyhus]

Mine for comparison:

 

[Sniperhandle]

Now that you have a better pic, You can see where the bottom of the shroud is galled. I think you are right, It is tilting or dragging.

That would be easy to figure out, Just reach your hand up there and center the shroud after cocking it before you fire a round.

If that's the case, You could weld up the bottom of the shroud and file it to fit.

 

[DShortt]

So I've not updated this thread in a long time. A bunch of unexpected things came up and I've not had time to look at it.
I got it out today and used a .015" shim to prevent the bolt shroud from rotating any and tried to pop the cap in a primed case. Had a very weak primer strike. Recocked the bolt, closed completely, then rotated the bolt handle back in the direction to open the bolt roughly .050" and the primer fired.
So apparently the bolt body is rotating enough to bind up the pin when it drops.
Now to decide where to place a small shim and how to attach it.

I'm thinking on the receiver itself directly under the bolt handle.

 

[akajun]

Drill and tap it for a small set screw and adjust it till you find the sweet spot

 

[DShortt]

Drill and tap it for a small set screw and adjust it till you find the sweet spot

That's an excellent idea! Thanks!

 

[Sniperhandle]

That's an excellent idea! Thanks!

Bolt shrouds are very hard, I would not try that. Most bolt shroud machine work is done after annealing, Then re-hardened.

 

[Liven The Dream]

A new spring is Zastava #7288. -Al