Sig P938: fixing it before it breaks - Kimber Forum


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Old 01-06-2016, 07:22 PM   #1
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Sig P938: fixing it before it breaks

If you have a Sig P938, you might want to think about the mainspring housing failures. On some first generation guns, the sear spring moves around, eventually grinding down the boss on the mainspring housing. This allows the sear spring to move out of position, rendering your pistol about as useful as a rock. There isn't any warning before the failure occurs--the gun works fine until you pull the trigger one time and find that it's become a rock.

A couple weeks ago I called Sig and asked them to send me out a second generation mainspring housing and spring. The gun has about 800-1000 rounds through it. It functioned flawlessly, but the potential for failure was a concern. They wouldn't do it, but said that if I sent them the gun, they would look it over, fix any problems, and install the new parts. Since the gun was over a year old, I would have to pay the $55 for shipping to them. Instead, I asked them to sell me the parts. Together, it was eight bucks plus six bucks shipping. Installing the parts myself would void the warranty, but who cares? It's out of warranty anyway.

Although I've never done this before, installing the new parts wasn't horribly difficult. If you're not comfortable taking apart stuff and putting it back together, you'll want to have someone else do this.

Here's a brief summary of the procedure:

Do a basic field strip of the gun. Pull out the safety, hammer, and mainspring. The pin that holds the mainspring housing is not tight. You can just push it out at this point. You can't slide the mainspring housing down just yet, as the sear spring will catch on the ejector.

You can push out the sear pin all the way, allowing the ejector and sear to fall free. Instead, I pushed the pin out just enough to allow the ejector to come out. Now you can pull out the mainspring housing.

Assembly is in reverse, but as you push the sear spring up, you'll need to use a chopstick to push the two fingers of the sear spring into position. Keep an eye on the sear, as it can spin around and you might not end up with it right side up. You can put the ejector back into place, then push the sear pin back. If you find that the sear is not in the right alignment, you can still rotate it around. Gently push the mainspring housing all the way up, and replace the pin. Replace the mainspring and hammer. Now you can test the functionality of the hammer, trigger, sear, reset, etc. Since you were careful, everything will work perfectly, but it doesn't hurt to double check.

Attached are a couple pictures. Look at the Gen 1 MSH. Note the polished area around the top where the spring moves. Also attached is a video showing the of the two pieces right after I removed them. I was very surprised by the amount of movement. I don't know if this is the way it's supposed to be, but the Gen 2 parts are rock solid.

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Old 01-06-2016, 08:44 PM   #2
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I thought they were lifetime warranties
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Old 01-07-2016, 03:49 AM   #3
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Originally Posted by Cucamonga kid View Post
I thought they were lifetime warranties
Page 66
SIG SAUER warrants that the enclosed firearm was originally manufactured free of
defects in material, workmanship and mechanical function. For the lifetime of the
original purchaser, SIG SAUER agrees to correct any defect in the firearm for the
original purchaser by repair, adjustment or replacement, at SIG SAUER’s option,

with the same or comparable quality components (or by replacing the firearms at
SIG SAUER’s option); provided, however, that the firearm is returned unloaded and
freight prepaid to
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Old 01-07-2016, 06:01 AM   #4
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How do you if your P938 is a Gen 1 or Gen 2?
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Old 01-07-2016, 06:26 AM   #5
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Call customer service with your serial number and they should be able to tell you.

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