If Sig said that the Sig P320 Spectre Comp will fit holsters for the P320 XFull then they should be compatible.
No, the Spectre Comp only fits X5 and X5 legion holsters. The 3 are 3/16" or 1/4" longer than the X series Full size. The 3 bottom out on the holster's barrel index pin/block before locking into the ALS retention. The holster can be modified by removing the index pin/block and heating to permanently widen the bottom of the holster to let the comp slide all the way in but it DOES NOT work out of the box. The Spectre Comp is also a little tighter because the slide is more squared off and blocky on the top vs the XFull slightly rounded top and melted corners.
My P320 Spectre comp Actually fits in my M 18 holster Rig from tier 1 Quarter inch of the barrel sticks out the bottom tho
It does not fit . You need the. X five holster my suggestion is to get ahold of rds gear