I warned you I'd probably use 'Quantum Leap' for a 'Rifleman' splainin eventually.....
Beyond the lifetime of Dr. Sam Beckett, the 'Quantum Leap' technology would be refined and improved until a leaper could pinpoint exactly his target choice to be the "leapee" and be able to leap back quite a bit further than his or her own lifetime.
But the U.S. government probably took control of the experiment away from Dr. Beckett's team to keep it from falling into enemy hands. However, like the secrets of atomic technology and the cloaking device, it would eventually get out. 'Quantum Leap' technology would be obtained not only by other governments, but by rogue terrorist cells and by individuals wealthy enough to start up their own facilities.
One of those wealthy individuals could have been this man from the future, whom we'll call "The Time Traveler":
And for some reason he was obsessed with visiting North Fork, New Mexico, in the mid-1880's.
"Outlaw's Inheritance" - episode 38
"Boomerang" - episode 39
"Panic" - episode 47
"The Jailbird" - episode 73
"The Promoter" - episode 87
"The Wyoming Story" - episodes 96 & 97
"The Stand-In" - episode 114
To the audience of the Trueniverse, each of the characters who were the leapee targets would like the character Dabbs Greer from the future. But to the citizens of North Fork, he looked like the person he replaced.
And while his leapee victims were in linear order along the Toobworld timeline as seen by those around him, his trips back in Time to North Fork could have bounced him back and forth chronologically from his perspective.. His first leapee victim could have been the last role played by Dabbs Greer on 'The Rifleman', not the first.
Here's the order in which I think this Time Traveler leapt into those lives from North Fork:
"The Wyoming Story"
|Researching North Fork, New Mexico....|
I think he kept returning to North Fork because he was intrigued by Lucas McCain, whom he met in Wyoming while he was assuming the identity of the local sot, Finney. And so he kept returning to North Fork to further interact with McCain.
Eventually the trips must have been insufficient for his kicks and he decided to get more involved in the life of North Fork - to the detriment of others. (It could be the continuing trips back and forth by leaping gave him a "swiss-cheese brain" and caused paranoid dementia.) For example, as Farley Steel upon his release from prison, the Time Traveler looks to have claimed "primo noche" with Missus Steel, if you know what I mean, nudge nudge wink wink.
But when he leaped into Jack Scully, the Time Traveler nearly got himself killed by the doltish fast gun for whom he acted as a promoter. He was able to leap out of that timeline and let the original Jack Scully return just in time to be gunned down by Ruben Miles.
But the Time Traveler wouldn't have blamed Ruben for the near-death experience; he would have seen Lucas McCain as the instigator for opening Ruben's eyes to his deception. And so he would have leapt back into the fray with the intent of getting revenge on the Rifleman......
He would have leapt farther back in time, to when the McCains were housing and caring for a young couple who had yellow fever. Taking over the life of a former Civil War vet by the name of Brett, he tried to stir up the town against McCain for putting them all at risk. By doing this, he hoped the others would burn down the McCain ranch-house. But Lucas was able to persuade them to fight their fears and go back home.
You can tell by Brett's swagger that he was not licked yet, and that he would leap back into the 1880's in order to take another shot at Lucas McCain.
This time the Time Traveler came back into the life of a Yuma prison guard named Taylor and he came up with a plan to get revenge on McCain. He engineered the escape of a prisoner in transport, making the criminal think it was his idea. And then he suggested the perfect substitute to take back to the Yuma prison in his place:
"That big mouth Sodbuster yesterday. He's got yeller hair, about the same size as Croft. Like you say, if we mess him up some, who’s gonna know the difference? We can get back at the sod buster – threatening us like he done!”
And so Lucas was kidnapped by these two corrupt prison guards and was being transported back to Yuma when there was a falling out between the two. As Taylor, the Time Traveler tried to make a subtle suggestion to his partner that they would be better off letting McCain escape. To his way of thinking, the Time Traveler probably hoped to shoot McCain dead as he tried to get away.
But his partner misinterpreted Taylor's suggestion and saw it for weakness. So he shot Taylor dead before he could tell the Yuma officials what exactly happened. The Time Traveler was able to leap out and send the real Taylor back to take the bullet meant for him.
This is why temporal enforcement agencies were created. A 'Timecop' would have been dispatched to neutralize the Time violator before permanent damage could be done to the timeline.
Maybe it was Jack Logan, or Captain Jack Harkness or Captain Jon Hart or agents Lucsly and Dulmur. But some time agent would have been sent back to eliminate the threat posed by the North Fork visitor from the Future.
The time agent may have even leapt into the life of Potter, the other prison guard*, but was then unsuccessful in killing the Time Traveler as Taylor. So as a back-up plan, he arrived in the saloon just before the Time Traveler leapt into the life of boozed-up farmer Sam Elder and surreptitiously poisoned his last drink.
As Sam Elder, the Time Traveler probably decided to play out the life of the drunkard while he waited for the chance to attack Lucas McCain once more. So, along with his "son", he confronted John Hamilton the banker over getting an extension on his credit. By this time, the poison was taking effect. After being refused by Hamilton, "Sam Elder" staggered out into the streets where he died, too far gone to activate the leap home.
|"Where am I?"|
To make right what once went wrong, the time agents would have had to find some new life for the real Sam Elder once he was released from the waiting room in the Time Traveler's 'Quantum Leap' apparatus. Since Sam Elder was considered dead in the 1880's, he couldn't go back there. Instead they probably took him to another spot in the Future, perhaps to the 30th Century. There he began a new life, perhaps got a new wife, and then raised a son named Paul who would grow up to become a communications officer for 'Space Patrol'. And thanks to tele-genetics, Paul would look just like his dad, Sam Elder.......
Hey, it's pozz'ble, just pozz'ble......
* Another quantum leaper rather than a 'Timecop' would be a good splainin for all of the Richard Devon roles on 'The Rifleman', among them Potter the prison guard.