I haven't really experienced any differences between the 1.gen razors which has always made sense to me considering the similar head geometry at least on the outside of the heads, but maybe the eg. blade exposure is different. I guess I will have to do a round of tests in the near future and likewise compare with the 'Popular'-models. Although the difference seems to lie in the total weight considering the thinner handle. 'Popular'-razors weighing about 61g it seems.
That being said the 1.gen razor came in quite a few versions through the years which makes sense in terms of transitioning periods.
What makes the weight difference is the construction of the t-bar or at least a big part of it. The ones weighing 76-77g have a t-bar like on the first picture which is what you are calling low bolt join. The high bolt join is like on the second picture:
But that is just one of the traits. The total number of different versions depends on how many of the following traits gets considered:
1) Low bolt join vs high bolt join
2) Wings or no wings
3) Silver, Rhodium or Gold plating
4) Writing or no writing on the two bands on the handle
5) Smooth bands versions came with a wide top band and a less wide top band shown here:
6) Different cases
7) Razor sets for the French market
-The same could be said about the 'Popular' models where most of the traits listed above are relevant too.
That being said the 1.gen razor came in quite a few versions through the years which makes sense in terms of transitioning periods.
What makes the weight difference is the construction of the t-bar or at least a big part of it. The ones weighing 76-77g have a t-bar like on the first picture which is what you are calling low bolt join. The high bolt join is like on the second picture:
But that is just one of the traits. The total number of different versions depends on how many of the following traits gets considered:
1) Low bolt join vs high bolt join
2) Wings or no wings
3) Silver, Rhodium or Gold plating
4) Writing or no writing on the two bands on the handle
5) Smooth bands versions came with a wide top band and a less wide top band shown here:
6) Different cases
7) Razor sets for the French market
-The same could be said about the 'Popular' models where most of the traits listed above are relevant too.