What about the gun that was on the drug runner that Locke found? It was taken by Sayid, and last we saw it was in Abandoned. Are we to assume that that gun was added to the stash of arms, or could that be a vital oversight? Or maybe the answer is something obvious I missed in my research?

Pretty sure Jack said that there were 6 guns in the box when he handed it over to Locke. That counts for the 4 9's that were in there originally along with the Marshall's side arm, and Goldy's gun.

Yup, he said all six are in there.

Yep, just rewatched the episode and caught it myself. Looks like it was a case of not doing my homework after all. :ohwell:

... and Michael's out there with one too.

He's out with a rifle, the gun count is of the guns that were in the case + the one that Sawyer found on the marshall. The rifles were in the hatch already, so they don't count.

Well I think you can safely say you've accounted for all of the pistols...