Winchester 75 premature fire

[Choatecav]

Just bought a Winchester Model 75 target .22 rifle at a gun show.  Was manufactured in 1949 and looks in wonderful condition.  When I got home I wanted to run a magazine of rounds through it so I loaded the mag with 5 rounds and inserted it into rifle.  Upon using the bolt to chamber the first round, the rifle fired!!  I kept it in a safe direction and cycled the bolt through the remaining rounds and all went as it should with no discharge.  Thinking it to be a fluke, I repeated the process and again it fired upon chamber the first round but no problem with remaining rounds.  I did it a third time and same results.  I removed the bolt and it looks good and clean.  Any ideas on what might cause this???

[Garufa]

Sounds like the firing pin may be getting sticky from crud.  I would disassemble the bolt for a deep clean or blast it with aerosol Remoil,  it’s good at loosening up fouling.

[Choatecav]

Thank you, sir.

[Sunfish]

Dried grease in the bolt I suspect. It may need to be disassembled, cleaned and lubed again.  

[Sidecarist]

I have a similar 75 that was my dad's. The trigger in these is very simple, and has a sear engagement screw. These frequently get adjusted to the bare minimum engagement in an effort to lighten the trigger. This makes things touchy when closing the bolt. 

Target shooters will accept this to get a better trigger but muzzle discipline is critical.

The fix should be obvious when you look at the trigger with the stock off. 

[DaveTN]

13 hours ago, Choatecav said:

  Any ideas on what might cause this???

The trigger is set too light or Bubba has been in it.

The interesting part is that you say it only happens when the mag is inserted and the bolt closed. If it was dirt it should happen other times. It should also happen at other times if it's the trigger, but the fact it only happens when the mag is inserted would lead me to believe its trigger related.

That's just a guess though, good luck in finding the problem.

 

[frankmako]

As with  any  older and/or used  guns that you pickup used, you need to break down and clean.  Then you need to a safety/function check making  sure the gun is safe and will work as it should.