Only goes bang on DA pull

[roso67]

So I took my newly acquired Sig P229 to the range today. I fired off about 50 rounds when all of a sudden I started getting light strikes on the SA pull, but it then would fire on the DA pull.

From this point forward sometimes it would fire in SA and other times only when in DA. Now it pretty much won't fire at all in SA. Any ideas? possibly the firing pin spring?

I am thinking I should just send the slide off to Sig or is there someone near Central Mass who works on sigs?

 

[matt]

How many rounds have been through this gun? Is it clean? lubed? have you ever detail stripped it? replaced springs?

These answers might help the diagnosis.

 

[roso67]

The serial number starts with AF so I think that dates it back. I got it used but it looked pretty well cleaned and oiled when I stripped it. I did not detail strip it nor have I replaced anything yet. I have both a .357 and .40 barrel and it had the same issue with both barrels and ammo.

 

[drgrant]

Someone may have changed out (or cut coils off of) the mainspring to lighten the pull... and they went too far. The dynamics of the spring change a little from SA to DA, so that may explain why it kinda worked in DA but not SA. (At least that's what I've observed while conducting experiments with wolff reduced power springs. )

FWIW if it is just the mainspring, you can safely use the Wolff spring that is
like one step below the factory poundage... just make sure you change it out after you put 3000+ rounds through the gun.

-Mike

 

[roso67]

Thanks for the reply Mike. I will have to check that out when I get a chance.

 

[roso67]

Someone may have changed out (or cut coils off of) the mainspring to lighten the pull... and they went too far.
-Mike

Just got this back a week or two ago, you were spot on. The spring had been cut.