I gave that as a good example of them doing gun sizes right. And most of the TAK releases have been really good about this. But Boardng Shotguns continue to be undersized on female Ariadnans. And the Spec Ops was a huge step backwards. Other than her Chaincolt/Heavy Pistol. All of her weapons were insultingly tiny. Pretty much to the point of looking terrible on the model. There are so many internal problems that come with just scaling down guns to fit someones body size. And many of those issues have been brought up in posts above.
Aside from what @Mahtamori points out, this isn't the case. I was going through my unassembled Invincibles stuff and I picked up the Combirifle Haidao, a model for a bunch of garbage profiles I'm never going to assemble, and I noticed his gun was a little different. It actually turns out the Yu Jing combi rifle has a telescoping stock. On closer inspection holding the pieces together, the Haidao's combi rifle is actually the same scale as the one the female Zuyong is wielding in the same picture. The Haidao in general are huge bois and he hulks over the female, but CB made the combi fit him by using the telescoping stock. I just thought that was kinda cool.
It's quite a recent and very very welcome trend. I noticed adjustable stocks on a couple of Spiral Corps models I was painting, like the Taagma schemer. Good on whoever is sculpting these.