I did it with 6 Dasher rounds and it seemed to work pretty well. So, I had PVA spin me up a barrel for it. In actual firing conditions however, the rounds would not feed reliably. But there turned out to be an easy fix. PVA also makes a magazine conversion kit that is inexpensive and very simple to install. The rifle now feeds reliably and is a laser to boot.
The only issue (if you want to call it that) is that due to the sharp 40 degree shoulder on the Dasher case, the bolt sometimes catches a little on the next round when you eject the fired case. Not enough to cause any problem from a functionality point of view, but it does make the bolt cycling a little less smooth than it might otherwise be. Cycling the bolt firmly minimizes this.
Since 6 BR cases use a 30 degree shoulder, this may not be an issue at all. The magazine conversion kit works equally well with 6br.
