I have recently acquired a Sig Sauer P226 in 40 S&W. It has a rail and has a German frame and an Exeter slide. SN is U 681 703. Can anyone help me with the manufacture or shipping date or refer me to an available reference for that info? Thanks.

If you have the box the DOM is usually printed on the label in small print .
At least it is on the factory plastic boxes .

They usually have a 2 letter code on the underside of the frame near the muzzle. A=0 -K=9. Hope this helps

Thanks, but I don't have the original box. I have contacted Sig Arms Exeter about it, so I'm hoping they can tell me.

Thanks! I checked into that, but it only applies to the guns whose slides were made in Germany, not one with an Exeter slide like mine.

The date codes are hit or miss. You can contact Sig but they lost the data prior to 2012 I think. This Thread on SigTalk might give you some clues on how to read your serial number.
Another possible method is to look at the sights. You might need a magnifying glass to read them. If they are original Sig sights there will be a two digit number code on them. It's not an exact science of course because the sights may have sat in a parts bin for a year or two before the pistol was built.

Thanks, Paul. That was very helpful and quite interesting!