Funny you mention it, I saw it maybe 7-8 years ago, then just a few days ago I bought the movie and watched it again. Yea, the bolt handle is a dead giveaway, as well as the film showing them actually using the straight-pull. I found it funny that when the two were shooting at cactus apples, they shot about 10-11 rounds rapidly, without reloading. Oh well. I would also imagine that not every general store out in the wilds of Texas & Mexico carried ammo for it.
Mark