I have yet to use these but when I received them in the mail I immediately opened the package and took a look at the thickness of the walls of the female bullets and saw that they were very thick and the craftsmanship was top notch.
I’d imagine that soldering wire to these is going to require a torch to heat up the bullets and once there is a melted pool of solder inside the bullet connector. At that point you’d take your silicone wire (which you’ve already tinned prior to doing this, untinned and cold silicone wire just shoved in there will not as easily create a proper solder joint) still at least warm from the tinning and insert it quickly into the bullet connector.
I wish these were more popular so that they would be cheaper but with the proliferation of the QS-8 and QS-10 (plus their anti-spark models) I think you’ll see more people opting for an XT style plug over bullet connectors. Bullet connectors still have their place though and I would always pay the extra to get genuine, quality connectors from Progressive RC rather than risk getting a low quality alloy connector on Aliexpress. There’s some things that aren’t worth pinching pennies on and your connectors that handle >50A are definitely one of them.