I don't shoot GSSF but I do use 3.8g of Clays with a 230g LRN in .45 ACP. I also use American Select and WST in the 230g LRN loads. Eventually I will use only American Select as the Clays and WST runs out.
I use 4.0 of clays with a 200 gr molly lead bullet in my 21sf. Have tried 3.8-4.3 with this bullet and they all worked fine. I have heard of people using as low as 3.2-3.3 of clays (having to change to a lighter recoil spring to cycle, but this wouldn't work in GSSF since you have to be stock except for unlimited class). Very soft with the 3.8 of clays, might be perfect for GSSF if it cycles ok. I ultimately settled with the 4.0, since I wanted enough to cycle well, but not too snappy like the 4.2-4.3 loads. I don't have a chrono but from what I can gather from others load data this is right around 165 pf to make major in uspsa also if you are going to shoot that any.
I have used 4.1 of Clays with a 200gr. X-treme bullet at 1.154. If you seat them longer they do not work. I used it in a stock spring 30sf in a couple of GSSF Major sub matches.
When I get a chance I want too try Eds load, with the 200gr. X-treme bullet.
Not sure what happened with the 1911 3.9gr string. Its low was lower than the 3.8 low, and its high was lower than the 3.8 high...so it's not like there was just one extra low velocity round that threw off the avg.
Even at Hodgdon's max recommended load, Clays just barely makes major. They did shoot nice though. I'll probably shorten the COAL about 0.01" and load some more. It's tempting to load some at 3.7gr to use for GSSF. I may try shooting some pins in the near future with 4gr.