To be honest, every single AR I've built from scratch has used a VFC box. Not only to have the bolt catch function, but because it costs less than other aftermarket gearboxes and is probably just as strong. Lonex and Modify gearboxes are made of similar materials but they're shiny, that's about it.
Also to note, if you do get the Lonex mechbox, make sure the bearing bushings are the 7 bearing version, not 8. The ones with 8 are terrible and fail quickly even in mild setups.
Originally Posted by lurkingknight
stick with the VFC gearbox if you can, the measurements on them are quite nice and the bolt catch of course...
No other aftermarket gearbox has the vfc bolt catch.
I also work on quite a number of vfcs and have never had this issue.