Savage 6a fires Full Auto HELP !!!

[UpandAtIt]

This one has stumped me. I have a Savage 6a 22lr tube fed Semi/Bolt made approx 1948. It was burping 2-3 round bursts. I bought new parts from eGunparts.com and Popperts Guns Parts; sear, trigger, springs (to include the recoil spring) and firing pin. I reassembled it. Now it goes full run away auto until the ammo is gone after the first shot, kind of like a cook off on an open bolt Mac or other open bolt weapons. This is a closed bolt rimfire.

The back cap is screwed in all the way. I checked assembly against another working 6a and I honestly cannot find any difference. I even measured parts on the CMM at work and the difference is within +/- .0027 average for the bearing surfaces as compared to the working 6a.

This only happens when the bolt handle is in the position for semi auto use. In single action / single fire use, the BOLT does not do this. I thought maybe I was getting a shallow travel of the bolt and then the hammer does not lock back for semi auto use, but a slow mo film of it going full auto shows the bolt travels all the way back.

The only thing I have not measured yet are the various PIN holes of the full auto to the working piece, maybe some of the pin holes wore enough to dislocated the hammer and sear fit and function.

This happens regardless of ammo used. I will admit it does have an amazing night time fire to it with the flames comming out the side fins and the muzzle when using CCI Stingers.

Any Savage smiths out there know what might be happening ?

I need to get this fixed before the feds say it is intentional.:banghead:

 

[Taurus 617 CCW]

My suspicion is that if there is a selector switch for single/semi it could be worn to the point where things are going haywire. Worn pin holes can cause what you described as well but it seems less likely. Unfortunately Savage does not service or repair any firearms made before 1995 due to liability. I suppose the only other option if you can't get it figured out is to take it to a local smith.

 

[UpandAtIt]

The Bolt Handle acts as the Semi to Single shot selector by a push / pull method. Nothing really to wear out there, just basically a very sturdy "cross-bolt" system that locks into the side of the receiver. There are more than a few bearing pins and pin holes that I am going to check this coming weekend. I talked to the Savage guy down at Popperts and he kind of just scratched his head and said he does not have a clue.