I sent Hornady 6 cases to make a two die form set to turn 357 magnum into a wildcat breech seat chambering.the case looks somewhat like a 22 jet necked to. 25 with more taper and barely a short neck.i was all excited when they arrived a couple weeks sooner than promised.
Well.. they missed the dimensions and they won't chamber.
The body angle is slightly off and the .25" long neck isn't there.
By not using a shell holder and ramming the case up in the die I got the back end to work.then I did the same in a .256 mag to get the neck to fit.
After $95 ea die(fair) and. $33 price to ship in a small 4"x4"  box(not fair) im a bit disappointed.

Surprised they didn't actually request to have a chamber casting also being sent to them.

Is a set of form dies designed to end up with the finished product or just to start with some other brass and arrive at a point where a normal full length sizing die can finish up?

I may be a little crude, but I would calculate how. much to take of the base of the die, chuck it up in a lathe and peal off the amount and brake the sharp edge and polish with a Arkansas stone, that's how I got my dies for 32 miller short to work, but as I said I may be a little crude---

You probably should have posted what they were willing to do before you posted all of the Negative. And then explained what had happened prior too. 
We once made a bullet mould and then cast several bullets with the same alloy the customer was going to use to insure it was correct. He sent it back and he said the bullet was not round so when I got it I fired up the lead pot. As soon as I opened the mould and there was a spot of alloy attached to the upper right corner keeping the mould from closing correctly. Cleaned it off, cast quite few bullets and they were all spot to size and round. If it was sent back he would have never have been happy with it so I cut him another new one and of course checked it and sent that one back. Now I we had a used mould and lost our ass on just that one mould. I was going to start making bullet moulds for sale and that one experience right out of the gate very quickly put an end to me wanting to do just that. So I just starting making them only for friends and myself who actually knew how to use a mould and what to look for and I did it at no cost other than possibly some USPS shipping costs and that was very rare as I also shot with most of these folks on a monthly basis.

Me we was myself and Barry Darr who lived with our Family for abit over a couple of years. He was the one teaching me how to make bullet moulds and allot more of what I never knew prior to. He was my best Friend and he had been going all the back to around 1998 and he was also a very precious part of my entire family. He was the one who actually taught and helped me to achieve all of my own personal goals that I had set for myself. We used to go out and shoot two times a week every week and more times than not using his Ohler Ballistic System that he also was willing to share with anyone who just happened to show up. We also set it up at least twice at our Clubs Yearly ISSA Regional match. So folks had a chance to gather realistic data right then and there. They would also receive a complete 10 shot data printout of what it was they were shooting at the time. All invaluable information as the system was the same as Sierra Bullets and others used in their own ballistic tunnels for bullet design testing and real time internal and external ballistic information.