Adventures in spot welding

I finaly got to try my new 220v Harbour Freight spot welder. It took two trips to the hardware store to get the proper 220v plug. I don't know why they make them so confusing. I chucked up the lower prong in my milling machine and modified it according to "gunnysmiths" instructions. I used a 1/4-20 copper bolt, turned down to the same contour and tip diameter as the stock tip. I did this for clearance purposes. I had some 4130 test pieces that were left over from some of my not so successful attempts to make my own receivers. I set everthing up and did my first shot....POW. Nice weld, but the tip (1/4-20 copper bolt) disintegrated! There was nothing left but the stub that was screwed into the prong. It is a good thing that I made two tips.
Second shot and ....POW. Same thing happened. It was then that I decided to modify the stock tip for a better fit. After modification, I tried it and got a good 10 test welds.....I was ready for my first rail!
** I used my first Tapco flat receiver...saving the best for later.***
I lined it all up and clamped it in place and got (what I think) four good welds.
I then set-up the ejector side rail. I did one good weld and then disaster struck! I went to do the second weld and the switch stuck! I have a nice 3/16 hole through the reciever!!! It must have been a fluke, because I went back to the test pieces to make sure the switch was functional. I continued with the ejector side until it was complete. Good welds, but not so pretty ! I guess I have a hole to fill on the ejector side.

All in all, I am somewhat happy with my first attemp. I believe spot welding is the way to go on these welds (much cheaper than a TIG welder and much cleaner than a mig welder).
I believe that the 220v spot welder is an overkill because you can't control the weld as easy. You have to bump the trigger, because it takes just a split second to weld and a split second and a half to burn through.
Sorry to be so winded, but I thought this was interesting.