Gil -
I'm not really researching the Powder River expedition, but the English rifled guns; so much so focused that I'd not really considered the make-up of the rest of the battery(-ies). The only types of guns mentioned that I'd seen were the English rifles and mountain howitzer. The 6-pounder and James rifle are real surprizes. Frankly, it was more of a hope that Battery L retained its militia battery guns, since I thought, perhaps, the English guns went to Powder River (that, I now know, is conclusively disproven!). I do have two questions : what is your evidence that Batt'y L retained two of the English guns? and what was the circumstance involving the loss of one of the English guns? But, I'll entirely understand if you don't want to reveal your hard-won sources!
John