The first cataloged #1s were the "B" Standard Sporter model in 1980. It was continued in the catalog until 2003.
There was a Wholesaler run through Lipseys this year of 250 #1s in blued/walnut "A" Light Sporter configuration.
The are a very very few that were made before the catalog era, 1980. I own one in 130 serial range and have seen one other.
There is also one non prefix "B" shipped from the factory in 1972. (Mine)
As for the 77. The first run of 257 Roberts were an uncataloged run made in 1972. The run was appox. 2500 rifles. They were on the long action (the 257 has always been made as a long action on the 77) the configuration was ST in other words it had a round top action and used the same scope bases as the Remington 700. The barrel was 24" and was of medium or magnum contour/weight and was furnished with factory sights.
The 257 was first cataloged as an "R" in 1975. It was produced through 1976 and then discontinued.
It was back in the catalog in 1981.
It has pretty much been around in each alteration over time So the re are tang safety MKIs, 3 position MkIIs and Hawkeyes. The vast majority are "R" or standard rifles with Ruger rings and no sights.
They have been made in many but not all variations of 77 over time. They made "RLs" in both MKI and MKII don't know about the Hawkeye.
Probably some "RS" sighted but with Ruger rings.
To the best of my knowledge they nevr made it in the "V" Varmint configuration.
Burke reported he thought there might be a few flat bolts and matbe a few hollow bolts but had to documentation. I've nevr seen either in the last 40 year.
Prices are starting to rise on tang safety MkI 77s in 257 Roberts.
Yes, it's my favorite cartridge and I have quite a few in #1 and 77.
Ross