Murrays or ? slams

OK So just got back from the range.
Trigger is positive engagement. Thanks Boris, I missed that.
Federal primers had a good dent when cycled through the firearm letting the bolt snap itself into battery. Slam fired and had one doubling, pull trigger once get two shots.
CCI 34 Mil-spec for 7.62 primers, small mark on the primer. NO slam fires, good ignition (Lawrys has the primers, I was the first to buy any, Price? maybe.)
SO what have I learned, soft primers on semi suck. saw small dents on AR 15 primers also when we could use them. AR 15 have light weight floating firing pins as the first ones had slam fire until the weight of the pin was reduced.
Stripped bolt and clean clean clean, dry dry dry,
Reload with hard primers CCI 34. Mil-spec.
 
The rule of the thumb is that the ideal sear-to-hammer engagement is negative-- i.e. the hammer moves backwards slightly as the trigger is engaged and before the hammer is released.


However, if you've got a gritty, heavy pull with resistance in the trigger pull -- just as the sks trigger was designed-- positive engagement is often not an issue at all.
 
cement head said:
Probably nothing wrong with the gun at all . as the gentleman said home made loads . it's more then likely the primers are too soft . brother try some good old military ammo and if it doesn't happen with it than it's the primers . have you ever ejected a round from a chamber and looked at it to only see a small indent from the firing pin ? well hence the term slam fire and as one jolly member said Mag dump . it's the primers .
Click to expand...

I've heard a number of accounts of American made 7.62x39 hunting ammo having the primers demolished being used in SKS and AK rifles-- because of the heavy hammer springs. As well as slam fires from volcanoed FB holes in the bolt face.

But I was not aware that there were 7.62x39 primers soft enough to fire from the forward motion of the freefloating pin...without the trigger being pulled.

Makes me wonder...maybe the earliest m43 design had softer primers? If so did the soviets switch to harder primers when they made the switch from springloaded to freefloating firing pin?
 
Federal 210Large Rifle, slam fire, doubles, big dent when bolt allowed to spring into battery

CCI 7.62 Mil- Spec small mark when bolt allowed to spring forward. NO drama.
 
Learn the sks, take it apart, clean the bejesus out of it, there are lots of videos on the subject. Treat all ammo as corrosive, all, and the firing pin should rattle when you shake the bolt.
 
OK the Murreys spring retracting firing pin just barley touch's the primer when the bolt is sling shoted to slam into battery.
Chambers and safely fires with federal Large rifle 210 primers, CCI 34 Mil-Spec, Small rifle federal, and factory GECO ammo.
So I am now good to go for safe shooting.

Yes I do understand cleaning the firing pin, but sometimes that may not be enough and something more is needed for safe operation. WHY? who knows? just do what is needed and move on.
 
NO, The bolt face is not different. I guess you may be thinking if the bolt face is scared or deformed or the firing pin hole is overly large but all is smooth and normal as best as I believe. The extractor is smooth and always functions well. Pitch's the brass faster and farther down range then the bullets like all Russian SKS.
 
can also be the trigger bar not properly seating in the safety notch on bottom of the disconnector arm.

I have one that did this. TEST WITH DUMMY ROUNDS. DO NOT USE LIVE ROUNDS FOR THIS TEST.

Ride the bolt down ... everything functions correctly, every time. Even if you pull hard on the hammer with a screw driven it will not fall. (because I have solid positive sear engagement).

Let bolt fly home as you're supposed to and the hammer drops every time.

This is the interesting part ... if I placed a screw driver under the disconnector arm (just set it in there, not jamming the arm up at all), the trigger worked perfectly every time I let the bolt fly.

Took awhile to figure out what was going on.
 
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