When did things like heavy barrels, glass bedding, free floating etc start to become more common? Also how popular were Unertl scopes for target shooters during the 1930's and 40s or was it mostly just iron's back then?
Prior to 1968 the Army financially supported the National Matches at Camp Perry. There were a lot of causes why financial support ended in 1968, part of it was that the Army stopped believing in marksmanship or marksmanship training, a belief codified in the adoption of the M16, and the assassination of Robert Kennedy and Martin Luther King gave the Army the political cover to walk away from financial support of the National Matches. However, prior to 1968, if you wanted to compete in NRA Highpower matches, you had to conform to the rules of the period, and they were written by Army, USMC, Navy, active duty and retired personnel. Active duty Military and Retired Military had the big vote at the table.
I have talked to many a Grey beard from the late 50's to the early 60's. The rules of the period were written so that you, the competitor, shot something like the service rifle. You can particularly see this in the configuration of the small bore rifles of the period. They had 3 pound triggers and the stock dimensions were "Garandish". The pre war rifles were "03 ish"
This is a 1939 ad for a Stevens M416
This is an H&R M12, made around 1981 and one that I bought from the CMP. It reflects the configuration of the small bore prone rifles of the 60's.
There are almost forty years between the two, there are differences, but they are slight. Neither of these rifles would be competitive in today's Small Bore game due to their heavy triggers and non agronomic stock configuration. The Army wanted Civilians to train with rifles that were close to the M1903 or Garand in configuration and so, the match rifles of the era were only allowed to deviate a little bit in stock shape.
From Bud's who shot Highpower in the 1950's, well you shot iron sights primarily. There was no such thing as an optical across the course rifle. For XTC, out to 600 yards, you used irons. Garands were very difficult to acquire. You could go the the National Matches and buy a NM Garand. State Teams had Garands and real M14's. Most club shooters used M1903A3's and held off on the target! I talked to the Club President about this, he competed at Camp Perry in the 50's, he said he was able to finally get a Garand in the 1980's. He bought an early Devine M1a in the 70's, to be competitive in service rifle. Once the M1a came available, serious civilian service rifle shooters walked away from their Garands and M1903A3's. The match rifles had a weight limitation that was close to a NM Garand (something less than 10 pounds), and you had a fixed buttplate. I doubt anyone used adjustable cheek pieces. One club member has a M70 match rifle from that era, very thin barrel, wooden stock, clip slotted action, I took pictures but I am not going to look at them. It was a rare rifle in original condition.
I don't know that much about the long range rifles. There had to be weight limits and I think there was an iron sighted and "any" category. I don't know what drove the any category. I have shot service rifle at 1000 yards and it is impossible, in my opinion. I used a frame hold, the bullseye gets washed out, my score was so low that I only tried it a couple of times. One thousand yard shooting is doable with an aperture front instead of a post, but still extremely frustrating to do. A scope really improves things at 1000 yards. As American's competed against the Russians in the Olympics, and lost, I know the small bore rules were altered so Americans, that is Army AMU shooters, could shoot rifles that were competitive at the International level. People today don't know what a big thing winning Olympic medals was during the Cold War era. The Olympics were viewed not as a competition between athletes, that is people, but between Nations and ideologies. Winning medals proved the superiority of the Nation and the economy theory, that is Communism or Capitalism. To prove Capitalism, and American Exceptionalism, was the best, Americans had to win Gold at the Olympics. So, small bore rules were changed so that American shooters could be more competitive at International events. What you see is that late 1960's Small Bore rifles began to change radically away from early 1960's service rifle configuration. Triggers changed too, early 60's rifles had three pound triggers, but, within a few years, the rules were changed to allow any trigger weight as long as the trigger was safe.
As for Unerl scopes. These long tube scopes fit on blocks on the barrel, like that Redfield 3200 on my H&R M12. Regional Matches are usually two day affairs, you shoot irons one day, 160 rounds, and then you shoot "any" the next day, 160 rounds. If you want to use the same rifle you have to have a convenient way to take off the irons and use a scope. These long tube scopes do that, and they do that with centerfire rifles too.
In my books and magazines, all the pre WW2 scopes that I see on rifles are long tube affairs mounted on barrel blocks. I don't know why they are all externally adjusted, maybe it was the technology of the era, and I don't know why they are all long tubed. Probably the same reason, but I am not an optical engineer.
Glass bedding seems to have been allowed in the early 1960's as the composite material became available on the commercial market place. I know the AMU developed a procedure on how to bed Garands with the stuff. Before fiberglass fibers and epoxy glue mixes were used, Garand stocks had to be shimmed between the action and stock, and even then, the wood compressed and the rifle shot poorly. Two part epoxies made for a stable rifle bedding and totally outclassed previous bedding practices. Once the Service Rifle teams approved the use of things for themselves, everyone else was allowed to use it too.
I don't have the NRA Highpower or Long Range Rules from the 1960's or 1970's, so I don't have an accurate chronology of the changes. But once the Army left the National Matches, the voting power of the Service Rifle teams was still dominant, but, since they were not bringing the big money to the table that they once were, civilians began to have more and more influence on the rules. Even so, recently the Service Rifle Teams rammed through an optical service rifle category in the rules, something not particularly popular with the civilians I know, but it will take time to see how things shake out. I am very upset that Dennis Demille,
http://bulletin.accurateshooter.com/tag/dennis-demille/ a retired Service Rifle Team shooter changed the rules to make the AR-10 a "service rifle". Prior to his rule change, a service rifle was a M14, M1a (civilian version) AR15 or M16, and the Garand. The Military teams were doing horribly against the civilians at 1000 yards with their AR15's. Civilians could shoot the 308 Win cartridge in their M1a's or even Garands. The rules were obviously changed so the military shooters could again dominate at long range, and with a rifle that was so similar to the issue M16 that hardly any training was required for military shooters to understand the thing. Service Rifle teams are again setting records with their AR10's so, what we see, even though now the Civilians are paying the bills, the Service Rifle Teams still get to write the rules to their advantage.