John,
Punching out thicker blades is not as simple an operation as most people think.
You are spot on with the punch having trouble.
Not that it couldnt be done, but to get the clearance between male and female parts of the dies, as the blade material squishes out under pressure, would require a new press tool with more generous clearances.
Even with a mate who is a back yard tool maker, thats going to cost a few thousand dollars.
Also, I would imagine the thicker blades, would require a new ferrule die, overwise the extra thick blades would give an oval shaped ferrule.
Another investment of a few thousand dollars.
Add to that, the spot welding would likely need to be reset to higher amps to get a solid weld, it's a lot of trouble and expense, for a very small market.
There is just not enough people who would buy the super heavy heads, for you to recoup the outlay in tooling up expenses.
I know people say wouldnt it be nice for....but its not quite that easy.
If you are ever interested in a new set of punch dies, I have a mate who is a back yard tool maker, but I have him busy for a month or two, lol.
I can pass on his name and phone number if its of any interest to you at some point in the future. He does good work.