These 'Slotters' cost around £245.00, (unless somebody knows where to get them cheaper) I offered him a Joggler/Punch but he insisted on a Slotter, apparently he does a lot ot Mig Brazing.
I think I have sorted this, it is called an oblong hole punch, it is made for punching holes in car body panels and is used instead of drilling prior to mig brazing..
see
http://www.wielanderschill.co.uk/html/holepunch.htm
Stainshield would be the Boc Gas to use, (Pure Argon) some of the forum members offer this gas in Non Rental Cylinders.. Welding stainless should not be a problem with your machine, no need to change feed rollers, some welders sometimes use a Polyamide liner but not really neccessary.
Paul
John, I don't think you can use your mig with gasless mig wire because of the polarity, these gasless wires run negative polarity and standard mig wire is positive. You will have to check with Murex(01992 710000 ask for technical on machines) to see if yours can be swapped over.
As for gas...
My name is Paul and I have worked for a welding distributor in the Manchester area for some 20 years.
The forum offers a great source of information and help, so if you have any technical questions I will try my best to help.
Regards Paul