My opinion is those shells are loaded with less than ideal purity of tss. Therefore they lack the weight of a higher purity. If these are factory loads of tss I’ve always had the suspicion they don’t buy the best purity and polished tss. There is a difference in tss and it’s not all produced equally. Back in the day before tss became commercially available I dabbled in procuring tss from china suppliers. I got educated on the quality fairly quickly.

I have never cared for #9 tss personally. My shot size preference is #8, this size has been very consistent for me over the years.

"Tomorrow is the most important thing in life.
Comes to us at midnight very clean.
It's perfect when it arrives and it puts itself in our hands.
It hopes we've learned something from yesterday."