Howdy Again
You have been given some bad information. Despite what the salesman said, revolver barrel lengths, all revolvers, all brands, are measured from the front of the cylinder to the muzzle, not from the front of the frame to the muzzle. I just measured the barrel on the K-38 pictured above and it is 5 15/16" long. That is consistent with a 6" barrel. They sometimes varied a little bit in length.
The Serial Number of almost all modern S&W revolvers is on the butt, not the frame inside the cut for the cylinder yoke. This particular K-38 had a lanyard ring at the bottom at one time, which is no longer there. I have blanked out the last two digits of the SN. Notice the K is way over to the left, so it would not be obliterated by the hole for the lanyard ring. The SN on a revolver of this age will also show up on the rear face of the cylinder, the flat under the barrel, and the underside of the extractor star. The SN of record is the one on the bottom of the butt, if the SNs in the other locations match up that means the revolver left the factory with those parts and they have not been replaced. This SN is K 761XX, and it left the factory in 1950.
The range for K prefix Serial Numbers for 1948 was K18732-K73121. The range for K Prefix Serial Numbers for 1949 was K73122-K84149. Smith and Wesson revolvers did not always ship in Serial Number order, that is why Roy Jinks, the official Smith and Wesson historian told me my K-38 shipped in 1950.
K frame target revolvers of this era had six grooves on the backstrap. There are also six grooves on the front strap. Later production Model 14s had ten grooves on the backstrap and front strap.
I suspect you are confused about the difference between a Hammer Block and a Transfer Bar. The thin slanted piece in this photo is a Hammer Block. This style of Hammer Block has been standard in all S&W revolvers since 1944. There were two earlier styles of Hammer Blocks, but I will bet you a donut the K-38 in question still has its hammer block inside. They were sometimes removed by foolish gunsmiths, but if you cock the hammer very slowly in good light you should see the hammer block retracting down into the frame as the hammer is cocked. Also, notice in this photo the tiny piece protruding into the space behind the trigger. That is a trigger stop. K frame target revolvers had these installed to limit the motion of the trigger after the hammer dropped.
This is a Transfer Bar in a Ruger Vaquero. It transfers the blow of the hammer to the frame mounted firing pin. S&W has never used Transfer Bars.
Judging from your photo the K-38 in question has a target hammer with an extra long hammer spur, and a target trigger, which is wider at the base than where it pokes through the frame. Difficult to see on your fuzzy photo, but that is what it appears to me.
You do not have a 'short stroke' hammer and trigger, there is no such thing in a S&W revolver. The hammer is a 'short throw' hammer. The distance to cock the hammer on any double action revolver is longer than the distance the hammer will fall when the trigger is pulled double action. That is just part of the design. On really old S&W revolvers, the full cock position of the hammer was back considerably further than the point at which the hammer would fall when the trigger was pulled double action. But it became obvious that the hammer spring was being compressed enough to fire a cartridge from the double action release point and there was no need to cock the hammer further for single action shooting. So a new style hammer was designed that did not require the hammer to be pulled back as far as the earlier designs. These were called the 'short throw' hammers because they did not have as much 'throw' as the earlier designs.
In this photo, the revolver at the top has a modern short throw hammer, the revolver at the bottom has the older style hammer. Both hammers are cocked for single action shooting. Notice the relative angles of the two hammers.
This K-22 Masterpiece has a short throw hammer with a long hammer spur.
This Model 17-3 has a short throw hammer with a standard hammer spur. Notice the trigger stop behind the trigger.
Sorry, I don't recall what I paid for the K-38 I have been posting.
Given the way prices are going these days, $800 is probably not unreasonable for a K-38 in good shape. $500 would be a real deal.