My apologies for dropping the ball and missing out on this thread. I had departed for New England and attended armorer's school while this thread was active.
A bit of digression for those who are not Sig owners. The Safety on the Sig P220 is an internal lever which serves to disengage the frame mounted Firing Pin Block. (If you remove the slide and look at the gun from the top. Going forward of the Hammer, you'll see the Sear Spring which is nestled by the left and right side of the Sear. Immediately to the right of the Sear is the Safety. It's that little table which appears less than 1/16" long). On the Sig, unlike other pistols, the Safety is not a manually operated externally located device found on the slide or frame.
That said, here's my take on what happened. The Safety is engaged by the Trigger Bar when the Trigger Bar is moving forward and cocking the Hammer. If the Safety is prevented from pivoting upwards, it arrests the motion of the Trigger Bar. This in turn prevents the user from cocking the Hammer in the DA mode.
Did what the gunsmith say make sense? I suppose rust or dirt can jam up th Safety. For the most part, the Safety is a very low maintenance part and provided the gun is kept clean, it almost always works. The peculiar thing about thequickad's Sig is that it's brand new and has only been fired twice - with factory ammo at that! I'm wondering if there is something about the range (fine dust) or the climatic conditions in thequickad's place that would promote rust that quick.
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Vigilantibus et non dormientibus jura subveniunt
[This message has been edited by 4V50 Gary (edited December 02, 1999).]