Once a relatively small photo is scanned, you can easily magnify and examine the details which are simply lost when looking at the original print. The following image is one of those details.
That looks like a small pistol, held by a women who I think belongs to the McKay clan. The entire photo is below.
Click on the photo to see a bigger image. You can see the three ladies on the left discussing the finer details of marksmanship. Obviously not treating the weapon in an appropriate manner, but that was well before our more sophisticated laws. The two gentleman in the middle are engaged in an entirely separate discussion…they may be arguing over who has the largest hat, but in any event the guy on the right has some strange hand gestures going. The lady immediately behind is simply trying to ignore the dialogue. Not much going on with the guy behind on the right, maybe he lost the hat argument earlier.
So this looks like some sort of camping excursion, unless they all have been kicked off a train for being too boisterous. Notice the luggage on the slope to the right. There is also some material on the ground at the far right, which may be some sort of tent. Perhaps then they have the shelter thing figured out. If the gun above is meant to address the food side, though, I fear they are not so prepared. That thing would probably be ineffective unless it was discharged point blank, and the local critters are unlikely to be so obliging.