Hmmmmm ... kneedown4GOD, well well, the plot thickens.
The heavy 230 gr bullet will provide enough "Oooommph" to cycle the slide of S&W 1911 even at below starting loads.
Do you have any other powder you can test load with? If the chrony is working properly, next I would suspect the powder as you claim the recoil was "a little weaker" than factory and your load is near max at 7.8 gr of HS-6 (Max load data is 8.0 gr).
If you get proper velocity with the chrony using a different powder, then it probably is your powder. Is it new/old? Any possibility of contamination or moisture damage?
Don't worry, I don't think THR gets "stumped" too often.