Allow me to make a correction. 1. The G27's do not have rails. 2. The "Frame Strength" scenario applies to older Glock 23's. On older G23 frames the "slide insert rails" were not of sufficient length for the slide velocity generated by the 357 Sig. If you have a new model 2nd generation frame or a 3rd generation frame, you're O.K. If in doubt, get the calipers out and check. Someone will probably post the exact measurements. Or, just call Glock to find out. The beauty of the 27 is that one can purchase a quality 357 Sig barrel and just drop it in.