Eagle27:

Re: The PH mounting system was poor although it was about all we could get for years before the Weaver system became available in NZ. The cone shape recoil stud protruding from the base of one ring into a corresponding recess in the one piece base was a piece of poor engineering as the cone and recess taper worked to lift the ring under recoil so needed the ring to be kept very tightly clamped to the base.

I currently use CZ550 30mm QR rings for PH BA24 bases. I replace the connector screw with a thicker head one or use washers to bring the head proud of the ring bottoms to act as a recoil stop.

These ones (sorry if I'm not allowed to do this):

https://www.tradeexcanada.com/content/cz550-2-pc-quick-release-mount-30mm-rings

For BB24 bases, I use the ones for the CZ527.