Out of curiosity I was perusing the Shellhole scenics and EWM websites to see what stage they're at with their Mex Rev offerings. While looking at the EWM US cavalry images I noticed that they're erroneously armed with carbines, when these units in fact carried the full-length model 1903 Springfield rifle – as correctly depicted on the OG 28mm figures.
What to do? Well, if you want Pershing expedition US cavalry in 20mm you can either ignore this somewhat serious blunder, I suppose, buy one of the other older brands such as Jacklex (assuming they didn't make the same mistake) or maybe wait for Shellhole Scenics to complete its range.
There is another possibility, though: use them as Constitutionalist Mexican cavalry, who were armed with a variety of carbines and rifles at first, but more likely to be seen with a carbine as they progressively regularised – especially in 1915. The EWM weapon would probably pass as a Krag-Jorgensen in this scale. Also, the ammo pouches don't appear to have the distinctively US triangular shaped flaps, helping them even more to pass as Mexicans.
For 1914 you could mix them with EWM's revolutionary cavalry, and for 1915, when uniforms were de rigeur, mix them with Shellhole Scenics' federal cavalry, with the latter perhaps having replacement heads in campaign hats.
