Civilian use of the Trapdoor?

[Ranch 13]

 With just 6 in total 45-70 cases found , and we don't know if they were the early internal primed or the later outside primed cases, we also have to remember that the Army did go back and supposedly survey the possibility of the shot, that's where the 1538 yds comes from, so it's not out of the possibility there were a few shots attempted at the distance by those engineers..
So who knows for sure, but we do know the possibilities are endless..but a trapdoor at the fight is doubtful at best.

[Oregon Bill]

The presence of .45-70 and .45 Colt cartridges at the Adobe Walls site is certainly a mystery, if they are associated archaeologically with the same stratum in which the others were found. The .45 Colt was very new as well; Custer's 7th was delayed in its Black Hills expedition that same year -- 1874 -- awaiting the new Single Action Army revolver that introduced the .45 Colt to the world. So we have circumstantial evidence that two of the newest martial firearms in the American military arsenal -- the Trapdoor and the SAA -- may have been in on the scrape.

[JimBob]

So who knows for sure, but we do know the possibilities are endless..but a trapdoor at the fight is doubtful at best.

That's my opinion.It is more likely those casings and cartridges originated from either the relief expedition or the two times the military was on the scene prior to the Indians torching the buildings.