Quality product with a caveat - GG&G GS-1 FIRE System Optical Mounting Rail

This GS-1 FIRE rail is well machined and mounted correctly on my DD M4 V5 flat top. However, the GS-1 rail will not correctly accept an Eotech G33 STS QD magnifier mounted behind an Eotech 512. I tried various configurations including removal of the G33 STS QD transfer bar and re-installing on the GS-1 rail only to find the GS-1 pinch-bar interfered by the G33 mount. Upon tightening, the GS-1 pinch-bar bowed under the G33 and therefore does not provide confidence due to lack of complete contact between the GS-1 pinch-bar and the flat-top picatinny rail; the risk of failure is not an option. This issue I am experiencing relates more to the Eotech mount as the GS-1 appears to accept other rail mounts such as a Troy BUIS and scope rings. Remedies would include milling the top of the pinch bar or the bottom of the G33 mount, neither options appear palatable at this time. In conclusion...the GS-1 appears to be a competent rail for devices with compatible mounts but NOT a G33 STS QD. I will be ordering a YHM rail as the pinch-bars do not interfere with the accessory rail.