I finally got a Redfield Base and rings for an Interarms MArk X I've had a while and went to mount it up today. Tightened the base down to the receiver, all is good. Took the front rings, assembled it together around a one inch diameter steel rod I use for this, put it in the base and began to turn it the required 90 degrees to lock it in. Seemed a little tight, I've mounted many of these before, but the bottom dove tail part of the ring sheered right off on me.
Now I'm back to waiting for another set of rings. I need to check the base carefully to make sure nothing on it was damaged. Really ticks me off and I have no idea what went wrong, these mounts are generally very high quality.