Yes, it was the Carbine Repeater and the Cattleman's Revolver. If you take anything else, then Dutch doesn't say his "good, let's get going " line, he just keeps telling you to get your rifle from your horse. And the mission won't progress, wasting lots of time.
I didn't do a good job of catching Kieran in the video, but it was good enough to get him in 40 secs (or whatever the target is) and to still hit the 15:30 mark.
But hopefully, it gives you some pointers and shows you that it is doable, even without a perfect run.