From the receiver readme “[TIGHT & TIGHTER TRUNNION] (I had too loose a fit on the Original Trunnion so I pushed the lip that interacts with the receiver lock higher. Use this version only if you find slop between the trunnion and lock.)”
My understanding is that there are different file versions for the receiver if you have tolerance issues. When Riptide tells you that its saying that the tolerances for their trunnion are meant to be compatible with the “standard receiver” file. Should work on the surplus stocks.
Having said that I haven’t printed one myself, just interpreting the files. Ymmv