Bill: I thank you so much for your input. I am not familiar with the term "no extension rib" and am wondering if by flat rib you mean the standard rib and not a raised or ventilated rib. My gun has all the features described above in my post and a standard rib (flat?). Could you please advise if you mean standard rib when you say flat and what "no extension rib" means as I have never heard the term before does that also mean a non raised or ventilated rib?
Thanks for your knowledge. Shame I will never know who this gun was built for as the records dont exist
