This is what I am using, if you want to know where I got it from still after this just message me, I don't want to advertise a different vendor in this thread.
The box for the bullet punch
The bullet punch with carto loaded
A punched carto
View of non-punched side of carto
This is a standard size carto and I did not mean to say the whole carto fits inside, just a large portion of it does. It comes with sleeves to fit smaller diameter items as well. You can plainly see it does not deform the carto at all, this was the first one I did and I am sure with a little more use I can get an even cleaner punch, as well as multiple ones without pinching the tube.
Forgive the color shifting in the photos, used my phone for these shots.