My PRO2009 has got the following symptoms:
9 out of 10 times the hammer fails to reset in the SA position after firing a shot and also when chambering a cartridge.
I thoroughly cleaned and checked the trigger group,out of the frame, but could not see any defects.
It does not feel very comfortable to see the hammer come to rest between the slide after each shot...

I have not torn into a DA/SA FCU (Fire Control Unit or the hammer box that houses the hammer,sear etc) on a Sig Pro.....from what I have heard it they are not an easy thing to work on. Is the hammer falling rather than staying cocked for a SA shot? It sounds like you are describing hammer follow.

Hammer follow is generally caused by Hammer/sear relationship...Short, worn or broken hammer hook.... Worn or broken sear...Trigger or sear not resetting due to insufficient spring tension.


Do you know the history of the gun? Total round count? Does it have a good track record until very recently?

When you take the grip off the frame and dryfire the gun can you see anything move differently? Two easy things to check would be the trigger bar pusher and trigger bar.....but it sounds like you most likely have an internal problem with the FCU. When you pull out the FCU and cock the hammer back can you replicate the failure?

Have you called Sig's customer service yet?

I would definitly be interested to hear how Sig Sauer Exeter N.H. deals with your situation. There are still a few LE agencies in the US using the Sig Pro so I would think Sig should be able to fix it for you......I have no idea how much it will cost though.

There are internal parts for sale on Numrich's website such as the sear, sear shaft, and sear spring......could be a fun project. here is the link to the parts list. http://www.e-gunparts.com/products_new.asp?CatID=8681

Some good news for you is that you can get a brand new DAO FCU from Numrich gun parts for $41.95 plus shipping.....the DA/SA FCUs are unfortunately much more expensive, typically running around $150-200+ depending on the website you visit.

Here is the link to Numrich's DAO unit.
http://www.e-gunparts.com/prod...&CatID=8681&mySort=1

quote:

Originally posted by stickman428:


I have not torn into a DA/SA FCU (Fire Control Unit or the hammer box that houses the hammer,sear etc) on a Sig Pro.....from what I have heard it they are not an easy thing to work on. Is the hammer falling rather than staying cocked for a SA shot? It sounds like you are describing hammer follow.

Hammer follow is generally caused by Hammer/sear relationship...Short, worn or broken hammer hook.... Worn or broken sear...Trigger or sear not resetting due to insufficient spring tension.


Do you know the history of the gun? Total round count? Does it have a good track record until very recently?

When you take the grip off the frame and dryfire the gun can you see anything move differently? Two easy things to check would be the trigger bar pusher and trigger bar.....but it sounds like you most likely have an internal problem with the FCU. When you pull out the FCU and cock the hammer back can you replicate the failure?

Have you called Sig's customer service yet?

Thanks for your prompt reply stickman428 !
Last evening I went over the problem together with a mate and a couple of strong espresso coffees.
We came to the same conclusion you just gave me,
hammer/sear problem.
I took the fcu out of the frame again and went at it with a stronger light and a magnifier...
There were signs of scoring on both the hammer and the sear breaking faces.
We decided to dismantle the fcu and try to hone the scored faces.
This went well but after assembling the fcu again we cocked the hammer by racking the slide
and saw the hammer go to the DA position spontaneously once more.
the breaking face had become too short.
The sear spring gives good positive force towards the hammer so we honed the interception notch in such a way that the sear would fall a little deeper into the hammer.
The angles on both sear and hammer weren't altered btw...
After reass'y we dry-tested the pistol again and found it now cocked to SA position very positively, without missing once or spontaneous
resets to DA position.
The gun will be test-fired on the range today !
The grouping, even with the malfunction, has always been consistent between 2 and 6 inches at 25 metres standing only stronghand fired.

This message has been edited. Last edited by: apexapex,

apexapex,

How hard was the FCU to disassemble?

I am glad to hear that you think it is fixed. I have not come across many posts on issues with the Sig Pro's FCU. Is this a very high round count gun?

quote:

Originally posted by stickman428:
apexapex,

How hard was the FCU to disassemble?

I am glad to hear that you think it is fixed. I have not come across many posts on issues with the Sig Pro's FCU. Is this a very high round count gun?

Hello again, stickman,
the pistol was put through it's paces yesterday and functioned flawlessly, one-handed, two-handed and from a rest.
The triggerpull , when against the pressure point is smooth, though a bit ;-) on the heavy side, about 5 pounds SA.
I bought it new and have fired about 12k rounds from it, both 115gr factory and 147gr reloaded
subsonics, the latter reducing both noise and felt recoil.
It's only used on ranges, not from a holster setup nor used for CC, since that's not allowed in my country (and would require extensive training...)
The FCU was relatively easy to disassemble, no
pressed in or fixed pins, everything is pushable by hand, with help from a cilindrical piece of brass or aluminium.
In the user manual is a good exploded view of
the weapon, including the FCU.
Both my mate and I are experienced technicians, though not in weaponry.
grtz, apexapex

This message has been edited. Last edited by: apexapex,