I have not fired that particular 223 barrel very much. I just got it and I am going to convert it to a 14" hole spacing. It will leave here on Monday.
I have 44 mag barrel that I was playing with when the screw bent. I was trying out a homeade full length 10" foream with the one screw. It may depend on how the forearm is mounted whether it bends or not. I had a lot of spacers between the barrel and the forearm, so the screw was lengthened in it's hold - if you can picture that.
I am guessing that on a 223 the recoil will be mild and it would not compromise the screw. As far as the POI shifting - well, the 223 that I have did not get fired enough to tell. I noticed it wouldn't group very good with some Winchester 45grs. Then I found that the scope base had some screws coming out and the rings were not as tight as I like. So everything came off and I decided to have another dovetail cut and an estuchion (sp?) installed for the 14" forearm.
With all that said, this must be a TC rifle forearm with a single hole already? or does the handgun barrel have only one hole? Was it a Contender forearm or the other rifle they built?