The type of rifles you describe, are actually in the minority. Many of those rifles were arsenal refurbished by trained REMEs. What most people don't seem to realize is that the Canadian, British and US makers of the Lee Enfields were held to rigorous standards, for the time, and all of their parts were and still are interchangeable.
It wasn't uncommon for them to have parts from every manufacturer in their respective bins. They made little, if any effort to make sure the rifles they were refurbishing were getting matched parts. Same goes for Garands. Serious Garand collectors shy away from Garands that have all matching manufacturers parts. The chances are very good the rifle was a put together or a regular issued rifle that was "enhanced."
Even the manufacturers of the above two firearms were notorious for mixing and matching parts. Especially wood.
My aunt used to work at the Long Branch facility and one of her jobs was keeping the stock fitters supplied with the various bits of wood. She commented that she really disliked the Savage contract wood, which were often made by sub contractors. Not because they were inferior in any way but because they didn't insist on drying the wood as well as their Canadian counterparts. She could carry 15 fore ends or 15 butts if they were Canadian or 10-12 of each if they were US.
I was interested and asked her about matching up the parts. She just laughed and said "Goodness No. We didn't have time for that and many of the fitters were on a bonus system. You just brought them whatever was available and on hand. Sometimes we would go for days fitting US wood and other metal parts. It didn't matter. They did try to keep all of the wood runs together though. It often happened that different wood was mixed together on the same rifle. Sometimes, they would stain the batches a dark brown, because they were to light in color. It all depended on the shift foreman and manager."
After a year in the rifle plant, she applied for and got a job in another facility where her job was polishing and deburring case mouths on 20 mm cases. She liked that job. She had a quota to keep up to and at the end of the week, if her quota was exceeded, she got a nice bonus.
She was a farm girl from Beisicker Alberta. She had never been away from home before and only made it into town twice per year. The free room and board as well as the good wages were just to good to pass up. They also paid her way to and from the city and from the bunkhouses to the plant. She told me they never had to leave the area. The company provided movies, dances, food, laundry services and lots of other entertainment. She joined an acting group and participated in several short plays.
Quite the old girl. She lives in Cardston now and her mental health is waning with time. She has had an on and off again battle with Cancer for the last 30 years and has been on a timed chemo drip ever since. Doesn't hold her back one bit. She goes to church 3 times per week and makes quilts and baby blankets for the needy. Her quilts and blankets are works of art. They would sell for big dollars but she always tells the buyers that she has more than enough to get by on and the babies need it more.
Yep, there I go again, running off at the keyboard. My apologies.
What I have noticed is that the truly "minty" so-called 'milsurp' rifles and pistols - the ones with magnificent fit and finish and with all parts not only matching but serial numbered to the gun - are generally ones that were made on a small contract semi-commercial basis
in peacetime.
As an example, the nicest German-made Mauser rifle I have ever seen or owned is one of the pre-WW1 South American contract models. It's a Brazilian Model 1908 in 7x57mm, made by DWM. It was made as part of a relatively small contract run, to commercial standards of fit and finish, as part of a commercial sale, and its original workmanship and surviving condition reflect that. Perfect bluing, near perfect wood, mint bore, all parts numbered to the gun and matching, complete with bayonet. It was one of the rifles bought as a 'status weapon' for the Presidential Guard, back in the days when the Germans were considered the finest military in the world and all the little banana boat republics wanted to copy them, and probably never saw action apart from being hauled out for honour guard duties.
Then there are the Swedish Mausers and the Swiss Schmidt Rubins. They were originally made by manufacturers who never had to ramp up for all-out war production, so again, every part is usually numbered to the rifle, and many are all matching. The rifles themselves were issued and used by forces doing things like border patrol, but were generally taken care of properly. So while 'mint unissued' is not common, 'all matching parts' with most finish remaining or with arsenal repairs to stocks is common.
Once you get to firearms made for the major combatants during periods of open warfare - especially the World Wars - all those small contract, semi-commercial niceties go out the window.
A British SMLE made by BSA just before the start of WW1 or during the first year or so of the War
might still have screws, sling swivels and barrel bands numbered to the rifle - and the numbers matching. After that, forget it.
And again, a 1930s SMLE or a late 1930s No. 4, might have left the factory with everything matching. But once the storm hit, what was truly important was production numbers rather than numbering the production.
I think bearhunter's aunt summarized the workers' priorities very well - on all sides: for some peculiar reason, they weren't in the least bit concerned about pandering to the interests of future collectors by making sure their guns were all properly numbered and matched. Instead, all they cared about was getting guns that would reliably go 'bang!' when the trigger was pulled into the troops hands as quickly as possible and in as large numbers as possible.
Perhaps bearhunter should scold his aunt on all our behalf for her lack of concern for our future needs as collectors!
One thing I found very interesting about what bearhunter's aunt said: I realized that a lot of stuff was sub-contracted and places like Long Branch didn't bother numbering small parts to the guns, although they might still stamp the manufacturer's name on each part. And I knew that the unit armourers in the depots or the fields didn't care at all about whose name was on the parts as long as they fit the gun being repaired. But I never knew that the major makers swapped shipments between them, so that Long Branch, for example, actually got shipments of wood stocks from the Savage plant in the US, and a Long Branch rifle might have left the Long Branch factory in Canada BNIB - with Savage wood on it.