In earlier editions SA had twice as many attacks than SS. In 5th SA only get one attack action just like SS. Balance wise SS became almost twice as "strong" in 5th when you compare them to earlier editions and SA.
How so? In the case of Long Arms, the SA/BF weapons are all much stronger than their SS alternatives: the PJSS has only 11P when compared to the SA/BF capable Enfield's 13P, and the SS Remington does only 12P compared the the 12, 13, or 14P of the other Sniper Rifles(only the cheap Ruger 100 does less). Anything using Automatics skill need not even be mentioned. In Light Pistols, the only SS weapon is the Taurus Omni-6, which does damage on par with the other weapons listed; not better at all(6P for the Taurus' SA mode is on par, and there are two other pistols capable of 7P damage at SA which the Taurus has to be in SS mode to fire, a distinct disadvantage). And finally in Heavy Pistols, the Ruger does do one more damage than the Predator, with slightly better Penetration, but 1P extra is nowhere near 'twice as strong'.
There is not a single case where SS weapons stand out as the 'strongest' in the bunch. The Ruger
almost outdistances the Ares Predator V, but with the new options from Run and Gun and the errata'd recoil no longer being the hindrance it was before the Ruger no longer really has any advantage over the Ares. Before the errata the Ruger had enough of an advantage for some people to consider it. But not any more. And I see so many discussions fall apart into arguments of what is the 'only choice' when it comes to builds, the Predator is going to be on every single one of those 'essential' builds for the most effective characters.
But were SS weapons so strong they needed to get nerfed to balance things out? Clearly no.
Now, my current character uses a Ruger, and even specializes in Revolvers. Because it's cool, it's fun to play. I don't get bogged down in what is or isn't the 'only choice'. So there's that...