Got a bit of an oddball here. I have a 1926 S&W Straightline pistol that has had the firing pin sear break, well it actualy sheared off. I have talked to a welding expert friend and they have determined I cannot weld up and machine it back down to spec, so I am left to remachine the part. But, I would love to have a blueprint of the piece, or some advice on finding someone capable of machining the piece. (It is hardened stainless from what I can tell.) Any thoughts or suggestions?

Never heard of a S&W Straightline.  You need more identification about the actual S&W model number.
In any case, if the gun was made in the 1920's, the part will NOT be stainless steel.
Stainless was not used in guns back then.

I'd suggest looking for a replacement part.
Here's some good parts houses:

www.e-gunparts.com/model.asp?idDept=230

www.jackfirstgun.com/
Possibly the best parts house, but you have to call.

Quoted: Never heard of a S&W Straightline.  You need more identification about the actual S&W model number.

They didn't use model numbers back then.  The Straight Line Target (AKA: 4th Model Single-Shot) was a single shot .22 LR target pistol.