The tip of one finger touched it. She strove no more for the rest. Up, she stood up to attention, with the muzzle beneath her breast.
She just gets the tip of her finger on the trigger, and she stops there. She stands up, at attention, with the tip of the gun under her breast.
By now we should be pretty curious about what Bess is up to. She's clearly got a plan, but we don't know what it is yet.
She would not risk their hearing; she would not strive again; For the road lay bare in the moonlight; Blank and bare in the moonlight; And the blood of her veins, in the moonlight, throbbed to her love's refrain.
She doesn't want the soldiers to hear, so she holds still. Besides, there's nothing to do now but wait. From what Bess can see, the road is empty and "bare in the moonlight."
See that moonlight cropping up again? It's everywhere in this poem.
All Bess feels is the blood in her veins, throbbing "to her love's refrain." Refrain is an interesting word there. It's a term for a repeated phrase in a poem, and there are plenty of those here. It could also be any repeated sound, say the sound of Bess's heart, or maybe the pounding of hooves. Stay tuned…