This is true. Unless you cast and size your own bullets it can be very hard to find bullets that are larger than the average size
Which is why most people equate lead bullets with leading.
In order to get bullets that will chamber in most guns, the commercial cast bullets are undersized for most guns.
The consumer, fearing leading, starts with very light loads, which don't obturate the bullet and bump it up to fit the bore. The consumers fears are confirmed, they have leading. But they are incorrect that the leading is because the bullet is not hard enough. In reality it is due to poor fit and a bullet that is already too hard for the light load they tried.
The consumer demands harder bullets, which are even less likely to obturate and fit the bore properly. Eventually the bullets are so hard that at safe handgun pressure levels, you can't get the bullet to obturate.
At this point, the consumer joins the club that perpetuates the mantra that lead bullets are a headache and not worth the effort.
I cast my own bullets. Early on I had leading issues in my 10mm. Then, one day I went to the range with some new loads. Instead of light loads with Blue Dot, I was testing some Unique, loaded for similar velocities to my Blue Dot practice loads. The faster powder gave a higher peak pressure, and my leading went away.
Upon educating myself, I found a couple of things. First, my gun's bore is oversize, slugging at .401. I no longer size my bullets, or water quench them to increase the hardness (yes, there is antimony in the alloy). I get no leading.
