You guys are such optimists... If I could have a dollar for every time someone told me they had an heirloom from their whatnot who was in the military and it turned out to be a sporter... 

 Not that a metford sporter isn't valuable, just not _that_ valuable...
Hope you are right though.
		
 
		
	 
Lots of people back in the day either stole, were allowed to purchase, or bought a similar firearm that was surplussed to replace the rifle they were issued in service. 
The prevailing trend was often to "personally customize" those firearms.
When large conflicts are over, firearms used during military service in the hands of civilians, is often frowned upon by the mainstream media and the often WOKE nose diggers they cater to. 
Not only that, but the people carrying those rifles were more interested in the "utility" of the firearm as a meat getter than preserving its history. 
So, they cut off everything they felt they wouldn't need, or made too much noise, etc. 
Large businesses were founded on customizing these otherwise unwanted firearms to make them more appealing to working class folks who felt a nice sporting rifle was a status symbol. 
Times have changed for many folks who want or like the look of the rifle's original design.  
They bewail the "molesting" of surplus firearms. 
They don't realize that what made many of our firearms traditions come into common practice would not have happened if those firearms hadn't been "customized." 
Many old timers who served tell their children, or whoever wants to listen, that they have a firearm just like the one they were issued. 
The listener doesn't really want to hear "just like," or just wants to believe the firearm was actually used by their ancestor while serving. 
Most nations required their servicemen to return their firearms to the armory upon release from service. 
The odd one may have "slipped through the cracks," but they are very rare. 
I knew one fellow who served during peace time, after the Korean War was over. 
He remembered the serial number of the rifle he was issued, as it was a requirement to memorize that number while in service. 
When he turned it in, right around the time Canada was starting to issue FAL type rifles, it had seen better days, but was still functional and clean.
In the mid seventies, he went to the local Hudson's Bay store in Vernon, BC, to buy one of the No4 Mk1 type rifles they were advertising in the local paper.  There was a big table, covered with as many rifles as it would hold, for customers to pick through. All had gone through an FTR. 
His first idea was to purchase one that had already been converted to sporter configuration, however, he found he could save $8 if he purchased an as issue rifle, and being a handy type, he could configure it himself. 
To his delight, he found one of the rifles bore the same serial number as the rifle he carried. 
The rifle looked as new, with a full FTR. New stock wood, fresh finish, and a new barrel, all covered in a fine film of preservative, but not packed in grease. 
The chances of such a find are almost impossible to calculate. 
Guess what he did? He took that heirloom home, verified the serial number from some of his release documents and receipts, then took it out to the shop, pulled off all the bits he didn't need while hunting, and promptly sawed off the fore end. 
Go figure.