Either the hammer or trigger has been replaced. From the factory, depending on exactly when built, the gun could have had either flash-chromed or color case-hardened trigger and hammer, but they would always match.

BTW, the barrel is not pinned in. It is screwed in and depends on torque to retain the barrel, exactly like current production guns. All the barrel pin has ever done is act as a safety to prevent the barrel from unscrewing more than a few degrees in case the barrel worked loose from shooting. The gun was still useable in an emergency, even if it was slightly loose. Guns made since the barrel pin was deleted in the early 1980s still come loose from time to time, and can be completely removed by hand without the pin to stop this.