Thanks for the information, I noticed the GPC barrels were finished with the front site post in place.
The last CBI barrel I installed was for a P14, the milled slot for the front sight key was a few degrees off from the index mark. Luckily the milled slot for the extractor was generous enough that there was no interference when final rotation was met.
I was concerned that with the gpc offering, there would be more than a few problems during and after fitting.
I think I'll stick with the CBI, all the other barrels I have sourced from them have worked very well.