We do a lot of gaskets, usually custom, where I work, and while the hole punch is great for some applications, we usually reach through the flanges with a die grinder and a coarse aluminum style burr and instant holes that line up perfectly.
I just priced & bought these All Pax Corp hollow punch sets and found best prices with Grainger same punches but Mahew name and also in stock at McMaster Carr www.mcmaster.com They are not cheap punch sets like many others and stack to make washers also. Something else you can do is look for a old hole saw with teeth worn out has the right diameter to make a punch from by chucking it in a lathe then grinding a edge on it makes good punch out hard steel. Guardaire bought out All Pax Corp and when I called they told me Fastenal & Motion Industries were dealers but went into their stores they knew nothing about these punches. Buy them online or Grainger or McMaster.
These are the best for rubber. I have punched hundreds of holes in conveyor skirting 1" rubber with them. http://www.csosborne.com/l-punches_1.htm The Arch punches from These guys will handle repeated abuse from a big a$$ hammer. The US General punches won't stand up to more than one or two smacks with a 4lb beater.