One thing you need to know is that heavier springs are thicker. This could cause what Bob pointed out but I am thinking now that the lower end may have missed the heat treatment room or failed to pass some other hardness test. Without having this gun here, it is very difficult to tell.
There is not Shok Buff or FLGR in my 1954 LW Carry Commander. I think that I stated clearly that I used them in my Toy Guns so we are not that far apart. I am open minded enough to think that there are various applications for these kind of parts. I think they extend recoil spring life when used in a gun that is shot in matches . Ed Head at Gunsite disagrees with me and simp[ly said "A $5.00 spring is not a problem to me!" I also think they save finger tips by eliminating "Pinch Checking." He said "We don't teach that any more." He did not say why or who's finger got shot . I value his opinion , but I build these guns, he just shoots them.
Most Pistolsmiths are Hard Headed, Arrogant, Opinionated, and very good at what they do. We all have different ideas and styles of work so we are all right, or we are all wrong. I prefer to think that their way works for them, and my way works for me. This is called "Free Enterprise" and is part of being an American. I do not use heavy recoil springs in 1911's . I use what the factory calls for in recoil springs ( I use a 16 1/2 lb VP in 45 ACP's) but make adjustments on the other springs such as the heavy duty firing pin spring, step down mainspring and magazine catch spring. I use a stock sear spring from Wolff and tweak it to suit my needs. My guns are not fussy about ammo and will generaly shoot any kind of ammo including 175,000 IPSC semi wad cutters. Thsi is what I like and tell my clients to use. I like to achive a well balanced gun. They are more fun to shoot!