From the earliest days the imperials always have shoulder mounted weapons for heavy weapons.
Through rogue trader to 2nd edition.
Then in mutation in 3rd edition they started imperials with underslung heavy weapons.
These chaos "havocs" you see here are from Rogue Trader.
The imperials are from Space Crusade.
Then in 97' the sisters of battle which were just released Sororitas miniatures got underslung weapons, and many were looted for marines for something different to shoulder mounted standards that had been around.
Looking through Eldar from the Space Crusade series again lately I see tat they also had underslung heavy weapons also, and not the platform mounted monstrosities they have currently.
Also back in the day it was the only way to get Shuriken carrying eldar guardians. As the plastic box sets they were releasing all have lasguns.
Oh my how things have changed, and deformed.
Relevance?
Modelling up the shoulder mounted Heavy weapons for the Sororitas Pre-97' SOB release.
Hee hee wow, only seen these guys once.
I've got over a company of them for a collection, all undercoat white at the moment. :)
With flexible weapons styles for tac/***/dev for the company.
I brought 5 boxes of Space crusade for $100 mid 90's. after getting a set when they came out, Plus many others over time.
My legion of the damned uses a squad of ten of them for one squad.
Handy with Marines over the decades.