I will never own another Kurt vise. In about 1997, I bought two 6” Kurt vises, one was very good, the other was junk. It would not sit flat on the mill table, it rocked back and forth about .015”, the other one was rock solid. I tried on 4 different mills and a couple of surface plates, the vise bottom had been machined wrong. I talk to Kurt, who said it was impossible, the seller said what I was saying was correct, they then said since I was a hobbyist, not a “professional shop”, accused me of stupidity, mis-use or willful sabotage. They were going to do absolutely nothing for me. I returned the good vise for full credit and eventually sold the bad vise to a shop, who had the bottom reground about .020” to .025” to get it right. I ended up loosing about $250 on that deal.
I ended up buying 2 Bison vises and had no issues. I’d give up machining and my home shop, before I bought another Kurt vise.
It just goes to show, as with most items, some people swear by them, others swear at them.