871 was definitely available with hand detacable locks. Old copy of catalog I had showed it with Boss type engraving like mine (below).
Here is a pic of mine. Only pic I have left and not quite up to my current size/quality standards of photo work.
There does appear to be one difference between the two that struck me. Mine had a noticably slimmer rounded sculpting of the action forward of the locks as it transitioned to the hinge-pin area fore-end. That is in addition to the rounded stock & action lock area. It is visible in my picture if you enlarge it, but the one on GI looks to be a straight/flat follow-thru of the lines of the rounded locks. That would seem to be more of the effect they used when rounding the 5xx series guns for G&H/etc.
Here is a Link that you can open aand enlarge to 150-200% to see the rebated frame forward and surrounding the locks.
